Black Keep boss glitches into columns and stays there

Game mode: Private server PVE
Problem: Black keep boss can glitch into a column and then ends up staying there. Ths is similar to the undead dragon in the arena glitching into the floor and staying there. Once in the column, he may come out again (we had him come out once) but he may also stay there the entirety of the fight. He can be defeated because he just stands there while you hit him and does nothing.

Region: North America

Steps on how to reproduce issue:

  1. Go into the black keep
  2. Fight the boss
  3. used the pillars in the room as cover from his ranged attack
  4. boss can rush the pillar to strike at you but sometimes rushes INTO the pillar
  5. boss is then stuck and stands there with part of his body sticking out.
  6. (optional) he MAY come back out again but often just stands there while you beat on him