why aren't more of the leading nations of the world stepping in to help make amends between these two countries and try to actively solve the recent Kashmir issue?

Many of the “leading nations of the world” have stronger incentives to either not to get involved, or encourage the conflict further.

Aside from India and Pakistan, there are several “leading nations” with interests in this region, and those nations view each other as geopolitical rivals, namely: China, Russia, and the United States.

China is seen as a potential threat by just about everybody in one way or another. In addition, China sees both India and Russia as potential threats as well. So they see a benefit in helping Pakistan defend itself from India, because the conflict with Pakistan keeps India distracted from potentially threatening China.

India has pursued foreign policies that try to defend itself against possible Chinese aggression. During the Cold War, this included a policy of being formally non-aligned between the Western Capitalist world (e.g. US, NATO, et al) and the Soviet Union. This was advantageous to India because they were in a position to accept military aid from the Soviet Union, without actually being a communist country. This arrangement was in the Soviet (and later Russian) interest because they too saw China as a potential rival ever since the Sino-Soviet Split in the 50’s.

The United States had little direct interest in the conflict with India and Pakistan (largely because India decided to be non-aligned) until 9/11. Then, it became advantageous for the United States and Pakistan to have good diplomatic relations, so that the US could wage war in Afghanistan against Al-Qaeda and the Taliban. That is currently changing because, 18 years of war later, the United States has come to see Pakistan as an unreliable partner in that effort for various reasons (e.g. lots of corruption, bin Laden was hiding there, they’re warm with China, etc).

With Pakistan being viewed as less important than they used to be to the United States, there is a desire for the US and India to have better relations, in part because they’re both concerned with Chinese expansion in the South China Sea.

So, the US and Russia want to be friends with India to counter China, and they don’t really like Pakistan that much. Even if they don’t want a war between India and Pakistan to take place, they aren’t going to want to aggravate India by forcing them to sit down Pakistan and sort their problem out. So, they both say stuff like “India and Pakistan need to figure that stuff out for themselves” because that sort of approach implicitly favors India without actually encouraging any wars there. Meanwhile, China doesn’t really like India, so if it has anything to say, it’s something that vaguely favors Pakistan in a similar fashion.

I mean, isn't that literally all the diplomats in UN and NATO and whatever do?

The UN has done quite a bit here already since it was founded...

Here’s a whole Wikipedia page about UN mediation of the Kashmir dispute.

This has nothing to do with NATO.

NATO is the North Atlantic Treaty Organization. It is a military alliance between the United States, Canada, and many countries in Europe to counter (originally Soviet) Russia and its allies. India and Pakistan have nothing to do with that, as it’s not in the North Atlantic.

Trump is by nature a foreign policy Jacksonian. This is a school of thought in the US that the proper role of the United States is to not interfere in other countries unless they have actively attacked the US itself, and that things like treaties and alliances only weaken the US when it does need to act. Anything the US does internationally is best done unilaterally or bilaterally (one-on-one).

From this point of view, nothing that happens between those two countries is likely to result in US citizens or soil being imperiled, so its not the US' business. Which is perhaps for the best, because a Jacksonian's idea of "getting involved" is generally a full-throated military response. No holds barred.

This is a pretty big switch from the postwar regime, where US foreign policy was largely guided by people from the three other schools of thought, who all felt that Jacksonian attitude was partially responsible for World War II. But it means you can't expect to see much enthusiasm for this kind of diplomacy out of Trump for the remaining 1 or 5 years of his presidency.

The answer is quite simple actually. The only dispute that the two countries have, is with regards to the territory that comprises of the Indian Union Territories of Jammu & Kashmir and Ladakh, and the Pakistani provinces of Azad Kashmir and Gilgit-Baltistan. India and Pakistan do not have any other disputes between them. Both the countries have signed an agreement in this regard that this is a bilateral matter. India has never sought external intervention in this regard while Pakistan has, despite signing the agreement. India has even refused third-party intervention whenever it has been offered. This is why there is no willingness by the world to step-in in this matter.

With respect to China in this regard, it is advantageous for them to have India, the next most powerful nation in the region, be permanently distracted by this. With regards to US, despite them needing Pakistan's assistance in Afghanistan, it is in their favour to keep Pakistan distracted by their conflict with India, because certain forces of Pakistan do have a role in the militancy that has plagued Afghanistan and will return to it if they are not distracted.

Also, with regards to what you call human rights abuses, it has always been a he said-she said thing, most often said by Pakistan and other sources who don't have any direct access to the people there. It is best understood directly from those living in Indian side of Kashmir and the remaining people of India, especially those of neighbouring region of Ladakh.

I'll take a contrary view and object that, in my opinion, there is a bit too much implicit expectation in this question that the India-Pakistan issue is solvable by outside intervention. It's not a bad question, and I've upvoted it, but its premise is a bit too optimistic.

Skipping past cases where there was already a victor and the international community brokered a cease fire, the list of peace deals brokered by outside parties in the 20th and 21st century is rather short. And a lot of it concerns cases where one of the parties was a much smaller state or a rebellion/liberation movement. In which case, sometimes outsiders can bring security guarantees that reassure the smaller party (thinking Good Friday, and the Indonesia - Timor Leste accords). Or maybe pressure a country to behave better towards its population, possibly by sanctions - South Africa in the 90s.

Pushing peace between 2 full-fledged nation states that are either at war or have been at war? The record is rather spotty. There were some initiatives during the Iran-Iraq war that amounted to precisely nothing (granted the goodwill and sincerity by the international community might have been lacking). And considering the rather high degree of animosity between India and Pakistan (a mutual dislike that seems to have popular support rather than being just government-driven), it wouldn't be easy to defuse their relations.

Add to it that the sympathy of much of the world with Pakistan is rather short and that India is a major power while Pakistan is still significant and holds leverage about Afghanistan and it's hard to see who would play the part of honest broker who a) favors no one but b) has to be listened to.

Where to start as well? India allowing a referendum in Kashmir would be a start, but that would be a red line for them. And it probably wouldn't solve much unless India lost it and respected it (a win would likely be declared illegitimate by Pakistan). On the other hand, the Pakistani military (who seems to decide quite a lot about how the country is run) - regularly slurps up quite a bit of its GDP. So their incentive to end this whole mess and downgrade their importance in Pakistan's civil arena is rather low.

(Occasionally there is a bit of pressure: India got blackballed by the US for a while for testing the 1998 A-bomb for example.)

Looking at the sorry fate of the Middle East peace initiatives since Oslo, a domain which the world has had much more engagement and interest and its hard to see how the international community can "fix" this. If the outlook is bleak, who's going to stick out their neck and put political prestige on the line to very little likely gain?

This is not to say that the present state of affair doesn't benefits some other parties and there aren't other motivations for doing nothing. But even if there were no reasons to keep this dispute simmering, turning it off would be really hard.

UN has discussed this as recently as Aug 15 2019

Pakistan wants UN to interfere and India has said that it a internal matter, India Controlled Kashmir is integral part of India. UN will have to interfere when India goes after Pakistan Occupied Kashmir.

Recently when Indian Prime Minister met with POTUS at G7 Summit, Modi told Donald that it was a bi-lateral issue and no foreign help is needed in this matter.

Summary:

The genuine answer is "any discussion is pointless."

Some background is essential to an undersatdning of why the answer to the question is as it is.

The core factor is that the dispute between Indian and Pakistan over Kashmir is a "holy war".

When India was divided into India & Pakistan in 1948, essentially on religious grounds, over 1 million people of all religious beliefs died for no other reason than that their beliefs were not acceptable to some others.

The Sultan of Kashmir chose (as he was told that he was entitled to do) for Kashmir to be an independent state. Immediately after partition Kashmir was raided by people who carried out violent and bloody warfare, very largely against innocent helpless Kashmiris whose beliefs were not acceptable to them.
Failure by the Indian & Pakistani governments to control the violence as well as they were capable of doing resulted in more unrest, more killings (of people of both major religious beliefs) and the loss of a possible opportunity to carry out a referendum of Kashimr's residents. The subsequent driving out of people entitled to be in Kashmir and influx of people whose views were predictable based on their origins, destroyed any possibility of a reasoned decision by the people concerned.

Subsequent geographical divisions and related decisions have not in any way addressed the now unaddressable core issues. NO decision except total assignment of Kashmir to Pakistan or India is acceptable to India or Pakistan.

The only acceptable solution for either party is that (from below)

The holy land must be regained.

The enemy must be defeated.

There is no other way.

SO In that context any attempts by world leaders, diplomats, persons of influence (or anyone else) are irrelevancies. Those who might choose to be involved are well enough aware of the 'impossiblity by definition' of their quest that their actions and attempts may sometimes be seen as being as token as they necessarily are.

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"DETAIL"

This is the short clear version :-) :-(.

If you think that you can leave any of the following out and still have any feel for the situation, beyond perhaps pure burning holy vicious hatred, you may be in for a surprise.

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And the great country of India rove itself asunder into two nations.

And, in the process, over a million of their number perished at each others hands, because it must be so.

And behold, all the little kingdoms and Sultanates and the like were told

• That they must choose to whom they should give their allegiance

OR

• That they might remain independent.

But, it was not true.

And behold, the most holy sultanate of Kashmir declared that it would remain independent.

And on the appointed day, it was so.

And the border people's of what was now Pakistan poured across the border into Kashmir and raped and pillaged and killed and drove out and carried off - goods and people both, they carried them away.

Those who were Hindu's fled or perished.

Some of those who were not Hindu perished as well.

And the border people's carried back much booty and people into the land whence they had come.

And both of the new nations on Kashmir's borders sat on their thumbs and watched.

(Much as the nations of the world did during the great time of sorrow in Rwanda,

and during the time of great madness in Cambodia (when at last the Vietnamese broke rank and put things to right), and as happens now in eg "West Papua" [tm].

For India to have acted unilaterally against the border people's,

may have been seen as an act of war.

For Pakistan to have acted against their own border peoples,

may have been seen like a really really good idea.

But, they didn't.

The looting rapine, murdering and carrying off continued.

After some days the Sultan of the most holy independent land of Kashmir appealed to India for assistance. And India replied, perhaps not ideally, but understandably

"If you want to live, come with me".

And Kashmir, having no real choice, went with India.

And India assisted Kashmir and the looting pillaging rapine and enslaving were terminated.

And lo, it was "game on".

And there were discussions and divisions and offers. And a referendum of the people of Kashmir was suggested. And India, surprisingly, agreed. But India, not too surprisingly, set terms relating to the removal of the post independence influx of Muslims into Kashmir before a referendum was held. But no action was taken by all when the opportunity presented. And there were massacres and driving outs and populations adjustments.

Hindu & Muslim, suffered they both.

And the opportunity for a referendum of the original people of Kashmir was lost with the killing, driving and mixing ups.

And so it was set in stone.
The land most holy must be wrested from the enemy.

There is no other bottom line.

It matters not

• What other nations say,


• what diplomats war-by-other-means war over,


• what honest-brokers propose

All this is of no relevance.

Until the still hour is come of the sea tumbling in harness the hatred and suspicion and death of brotherhood shall continue.

When election time draws near in India, the banners shall be waved and the divisions shall be made more divided, but these are but ripples on the surface of the fundamental issue -

The holy land must be regained.
The enemy must be defeated.
There is no other way.

All the above is believed to be based on historically accurate "facts".
I'h happy to modify any statement that there is a clear factual contradictory evidence on.

Opinion, disagreement and varied perspectives are all part of the territory in areas such as this.