Delirious Black Crow doesn't get Damaged

Black Crow doesn't progress to its third phase if fought in a delirious map.
I noticed when a delirious apparition emerges from the boss and it's health becomes low enough, it doesn't get damaged anymore and won't proceed to it's third phase where it runs to the small area where you usually end the fight.
Happened to me two(2) times already it I can't portal out because I'm in the boss arena.

here's the image