Black Crow Boss Bugged - Won't pick up bell

In a Black Crow boss fight in Blooming Field, ilvl 81. In phase 2 and he won't grab the bell, I spent over 5 minutes of him running around invulnerable to damage. I did get him to ~20% health before he stopped taking damage, possible phase skip.

I exited game, it loaded my back into boss encounter, ran around for another 5 minutes without progress.

Had to die and fail the map. :(