Molten Firestorm and Molten Berserker won’t spawn. Someone disconnected as we entered the area. No cutscene was played. We heard the narrative for the bosses, but we can’t leave the area without being teleported back. They aren’t spawning at all. Very sad to start over. 
Molten Facility bosses not spawning.
our party just experienced the same issue. end boss doesn’t spawn at all. unable to resolve issue. had to leave dungeon. when we exited the players standing outside the dungeon were complaining of the same issue. seems to have been introduced after the most recent (very small) patch that was implemented after the main update.