This happened to me too, the dwarven cities also kept vanishing from time to time.
Viewing post in Oriel and the Black Knife...v8.1 comments
Oh for the bug above, it is caused by entering the southern dwarf city in the South West. For some reason there are two that can be entered almost certain that is why the scene plays twice. The player is supposed to go through the top one I image (NW). I confirmed this and by going through the NW one I didn't run into the bug but I do still get the blocker if I leave through the region via the East Bridge.