So far this has happend in 3 areas. I go there, then the door appears to open but it's impassible or it just never opens.

In the base game, I was able to fix most of them by reloading from before I came in.

However trying to do the demon lord belial dlc, right after the guy snipes the demon, I finish off the enemies and now I'm stuck in the area.
The game auto saved AFTER this battle, without letting me out of the area.
Any fix for this crap or a way to step back to a save before that point? :-s