Hey, just saw this post while looking for anything about the problem I am facing, and I had a similair issue, but with the Underdark area as a whole. My issue started with my character being unable to move, but still visible, jumping and doing anything would not work, and the prompt would say that the character would be too far away, or out of reach. When I tried to go anywhere else (camp as well) the map would look like parchment, if visible, and I would have the same issue as you said (black screen but cursor, and some sounds, still working). What I did to fix this for myself was to verify the game files. The game then downloaded 1 GB and a little more of something, and the issue was no more from then on.
Not sure if it is the same issue, but I hope this helps in any way, best of things! :3
