Zolin, Blood Priest invincible at 0 hp (quest still completed)

https://imgur.com/a/GzLYQGy <-- can't seem to make the img tag work

Not the best screenshot, but after "killing" Zolin and Doryani shows up, the boss kept attacking and was invicible. Had to dodge his attack to manage to get through Doryani's dialogue

Not sure how to reproduce,
I am playing a full werewolf build
I killed Zolin with shred while lunar blessing was active