7/16/ still bugged but I figured out a work around.
What I did was after I engaged him and he got stuck in the spin animation and was immune to everything I ran away far enough to disengage combat, ran back and hit him with blinding light (any ability that dazes your target should work) and after he was done being dazed he went back into his regular combat mode instead of the spin… until I had him at about 25% health and he did it again so I repeated the process and was able to kill him