Basically, I've given Pyros the antidote, got the random ammo from him. Asked about assassins, Izbelah, and something else. Talked with Jasper, Lothar and all the Flamewalkers. No new dialoge options have popped up for freeing Izbelah as the walkthrough suggested or for seeing the play. I've played IWD2 before, but it was awhile ago and can't seem to remember what I'm doing wrong. Any help is appreciated.

Go back to Pyros' domain. It should show a cutscene where Venomin tells Pyros what happened, and Pyros tells Lothar to free Izbelah the day after.

Nothing like that happens. I've went everywhere and talked to everyone multiple times, no event ever seems to trigger.

I had a similar problem. It has been a while since I played but IIRC you have to be in a certain spot to overhear the conversation. Sorry I don't remember the spot. Hopefully someone else will. This is a very helping forum.

This is a known bug. This happened to me the first time I played the game and since I couldn´t get the patch everything was lost. Yours might be to since I dont know if the latest patch will fix it in the current game, but I know it´s fixed in any game you start efter you´ve installed it.