The common narrative I heard was that the Soviet army encouraged the poles to rise up in Warsaw to fight the Germans. with the expectation that the majority of the poles that fought were nationalists. The Soviets denied the allies the right to airborne drop supplies into the city, and they moved a mostly polish armored division away from the city.
This seems to hold water. especially when you consider the fact that it was not the first time they were cruel towards the poles. i.e. the Katyn Massacre. Also when you consider what happened after the war. The Polish nationalists were now outnumbered the polish communists and Poland became a satellite state under the Soviet Union.
Here is an interesting if somewhat unexpected source: https://www.marxists.org/reference/archive/stalin/works/correspondence/01/44.htm (Stalin/Churchill communications of 1944, emphasis mine)
No 322 URGENT AND MOST SECRET MESSAGE FROM PRESIDENT ROOSEVELT AND Mr CHURCHILL TO MARSHAL STALIN
We are thinking of world opinion if anti-Nazis in Warsaw are in effect abandoned. We believe that all three of us should do the utmost to save as many of the patriots there as possible. We hope that you will drop immediate supplies and munitions to the patriot Poles of Warsaw, or will you agree to help our planes in doing it very quickly? We hope you will approve. The time element is of extreme importance.
ROOSEVELT
CHURCHILL
August 20th, 1944
No. 323 SECRET AND PERSONAL FROM PREMIER J. V. STALIN TO THE PRIME MINISTER, Mr W. CHURCHILL AND THE PRESIDENT, Mr F. ROOSEVELT
The message from you and Mr Roosevelt about Warsaw has reached me. I should like to state my views.
Sooner or later the truth about the handful of power-seeking criminals who launched the Warsaw adventure will out. Those elements, playing on the credulity of the inhabitants of Warsaw, exposed practically unarmed people to German guns, armour and aircraft. The result is a situation in which every day is used, not by the Poles for freeing Warsaw, but by the Hitlerites, who are cruelly exterminating the civil population.
From the military point of view the situation, which keeps German attention riveted to Warsaw, is highly unfavourable both to the Red Army and to the Poles. Nevertheless, the Soviet troops, who of late have had to face renewed German counterattacks, are doing all they can to repulse the Hitlerite sallies and go over to a new large-scale offensive near Warsaw. I can assure you that the Red Army will stint no effort to crush the Germans at Warsaw and liberate it for the Poles. That will be the best, really effective, help to the anti-Nazi Poles.
August 22, 1944
To me that's seems 100% clear: Roosevelt and Churchille are asking Stalin to help their planes (I presume to use Soviet air fields/fuel) and getting a response that the uprising serves the power seeking criminals.
So, I think, the common narrative is basically correct (at least the part about refusing to help and interfering with British attempts to help)
Another interesting link: Soviet Broadcast to Warsaw on July 29,1944 http://www.warsawuprising.com/doc/kosciuszko.htm
Tangentially related: Katyn massacre archives http://portal.rusarchives.ru/publication/katyn/03.shtml
Zhukov's memoirs (ch 20) claim that Bor-Komorowski (the leader of the rebellion) actively refused to meet with Soviet representatives. Without cooperation from the other side and with troops exhausted by a recent offensive no significant help was provided
I don't fully trust Zhukov's account: at the very least he would have never been allowed to contradict the party line. BUT...
It does seem possible (in fact, likely) that the leaders of rebellion (being supporters of the Polish government in exile) could have actively refused Soviet help (or antagonized Soviet command in some other way) at least early on. In particular, if Soviet help involved Soviet army directly taking control over Warsaw. And then Soviet command decided to teach a lesson..
To be clear: even if this did happen, it was still a poor excuse not to help Warsaw.. But it does add a few shades of gray to the picture
and they moved a mostly polish armored division away from the city
accordingly to memoirs, pro-soviet polish troops were in fact allowed to join (and did join) the uprising forces (see Berling's army) But without the support of main forces that did not change the outcome