I tried doing this quest and got to the Veloth tomb and followed Dren all the way to the treasure room. When I entered, the quest was pointing me somewhere other than that room and so I went through the door I saw across from me. Doing so teleported me to the beginning of the dungeon, where I ran all the way back to the puzzle room with the vanishing wall, only to find the wall there again and completely unpassable. So there is no way for me to get back to the treasure room to continue this quest. Looking it up, people have been reporting this issue since Morrowind's release and it's
still not fixed. This quest is still broken. And abandoning it and redoing the entire thing won't fix it either, you'll just run into the same non-vanishing wall. It's horribly frustrating.
Edited by ShadowEevee128 on September 14, 2017 11:42PM