Seems like it's related to Hotfix 21 but we've been having the problem since we got into Act 3. It's bad enough that the spouse doesn't even want to finish the game.
I have a separate single player game and I haven't ran into this issue in single player.
We're in the same boat on our Tactician game together, we haven't played it for two weeks now waiting on a fix. We had planned to start another game with a third player and can't because this bug has gone unaddressed this long.
