Is it true that there were Indian POWs that were not released by paxtan during 1971 war? If so then what GOI did for them?

I have studied many articles regarding Indian POWs that were not released by paxtan. Paxtan lost the battle and we had released there 93k people then why the didn't released them.

Also the torture they did to Indian soldiers and the genocide of Bengalis in bangladesh why were they not sued by ICJ on the basis of Geneva Convention ?