I didn’t have this particular problem, but I did have a very glitchy one. When I finally killed the boss (Malevolent Memory), it killed me at the same time. Before I had a chance to do anything it went into a cutscene to which Marjory revived me during. After the cutscene was over I was alive, but the quest didn’t progress. I jumped back out of the chamber and tried to toss myself off the one of the ledges to see if respawning would help. When I did that, it ported me back to the very beginning but wouldn’t let me use any of the teleports to get back through, so I was stuck at the beginning. I had to log out to get out of the instance and now I have to do it all over again.