Game mode: [ Online private ]
Type of issue: [ Bug ]
Server type: [PvP + PvE]
The problem is that the boss is “missing” because he spawns undermesh like the Sewer boss. Often, like in the video, is a bit undermesh, dies right after the barrier is gone and you can loot it, and another times when it dies, will fall into the mesh and, obviously, you can’t loot it.
PD: if you watch the video you will see that he is also outside the barrier before you even kill the last ghosts.
PD2: I also tried in a free modded server - same issues.
Maybe because of this (if this is his spawn point, of course - no idea)