In the Druid Camp, heading into the cave, there's a scene where the mercenaries confront the Tiefling leader. I was unable to persuade the Mercenary to not punch the guy out, and after that he ran off, and my characters got exclamation points over their heads. I tried talking to each other, and it didn't work, then I switched characters, and tried talking to them again, and instead they all merged into one blob which was unable to move, and no conversation started. I was unable to save because it was in dialogue. I had to quit.
(Previous save was about 2 minutes earlier.)