Dracolich bug?

Has anyone seen where Dracolich aka the last boss in castle never will fail to reset after a wipe? His hp bar will be on your screen and hell be constantly spawning adds that will build up at the door. They sometimes despawn after a bit and sometimes dont. It also appears that this bug makes Dracolich spawn double adds during the encounter. Happened once for us after 3 wipes and we had to call it. Then the following night we dismissed companions thinking maybe they were causing him to aggro through the door somehow, and it happened again after 3-4 attempts.

Anyone seen this, know what causes it? or how to fix/prevent it ?