I have seen this same bug in other dungeons, but I know it always happens in Ulder’s Cave. As soon as you enter the room with the switches, you are instantly teleported to the other side of the room.
Theres another bug to Uldar’s cave. It says to saly everyone and the 2 remaining are immune to all attacks. They have total invulnerability and the only way is to end the game and restart. All that work