Dialog race condition

Sivar

I went downstairs to the Cult's basement and immediately exited.

Expected behavior: Dialog doesn't begin, or once it begins it prevents party transition.

Actual behavior: Dialog began with the downstairs characters while I was upstairs. This effectively locks up the game because no progress can be made as the dialog cannot progress, nor can I exit the dialog and move downstairs.

Balquo

Could you attach a save just before going down to the basement?

Sivar

Not anymore, no. I believe it should be reproducible with any saved game.

Does anyone else have a save not long before attacking the cult in their basement?

lefreut

@Balquo: I have a save just before going down to the basement

Sivar

Attached: I used lefreut's saved game and created a video. The outcome isn't exactly the same as my own, but it is strange.
The dialog begins downstairs, then there's a brief flash of NW Ulgoth's Beard for some reason, then the characters go upstairs. Going upstairs cancels the dialog without response.
If I go downstairs after the video, the cultists do not initiate dialog, do not summon the demon, and allow me to wander around.