I'm having the same issue. Werewolf stops fighting at zero health and just stands around. I've tried saving once I get into the fight. I've tried fast traveling to different maps. Werewolf is stuck in the same spot with 2/3 health and cannot be harmed. Seriously frustrating when I'm so close to the end of the game!
The most annoying things for players right now: undying werewolf, flying chair in oxenfurt, awkward animations for dockers... and nothing has been done with such issues..
3 months have passed, cdpr do you even care?!?!?!