Did u die on the final boss? Because i think it wasnt bugged the time first i battled him, however on our second try the crap started happening.
I experienced the exact opposite our first run through. The flames were present on the first wipe, not on the second attempt.
My second run through, no issues. Side note, if you're having problems, you can pull him out of the room by sacrificing a DPS. Have everyone out of the room, have the dps run in. He will die, but because the rest of you are in combat, the boss will run right through the door that spawned and attack you in the hallway. Fight him there for an easy kill.