All of the bosses in Wayrest Sewers were invisible to me, as the title says. All of their abilities were also completely invisible, but anything they summoned, like the ghosts against the first boss could be seen. All of the normal mobs could also be seen. I tried reloadui, logging out, and traveling to a group member, but nothing worked. We decided just to deal with it because I am a healing only player and don't necessarily need to see the enemies as long as I can see my allies. After the first boss, the healing bars glitched. They showed always at full health on my screen until the moment of death when they would instantly drop to zero. I was the only person in my group who had this problem. We ended up beating the dungeon only because I was able to spam cleansing ritual and let my group heal themselves as needed.