The same for me. But since the last update on May 4, one day before the Black Emporium became available. It adds a new challenging feature for combats. You never know if the PC or one of the companions will quit the combat. A new feature which I prefer not to have for boss fights. 😉
To toggle off the tactical camera doesn´t solve the problem for me. I can´t move the char manually as well.
There is a small chance that certain abilities like flank attack for rogues or lunge for warriors reset whatever is blocked. But there is no guarantee that it works. The success rate is probably about 30%.
I still have no clue what could trigger this bug. At least affected chars seem to be ignored by enemies. Beside the loss of responsiveness on selection it looks like if some char attributes would be cleared temporary.
Assignment of AI, group / combatant status ...