I have this bug as well. Loading the autosave from entering the room with Nemnok (accepted quest to save Kaali from the village) repeatedly to try new dialogue options. All with same result. Nemnok flies up from the pit and Kaali points towards the party then the dialogue event ends. I am unable to talk to Kaali at all and upon talking to Nemnok he greets the player as if they have met before with only dialogue options to ask him one question referring to the gods or to promise to bring him MORE grimoires (of which I cannot give regardless because I do not have a quest to do so). Essentially the only interaction available to me upon entering the chamber of Nemnok is to kill everyone in the room and loot the corpses/chests.
This is post most recent update. I have not encountered Nemnok before this latest update to collect data.