Its not a issue with the mob killed, i can kill mobs in a bandit camp (100% humanoid enemys) and it never works.
This is the nail in the coffin for Werewolfs. effectively making the entire tree useless.
As it was, it was already badly bugged, not working on new kills after devouring, often not coming back up at all...
Werewolf is nothing without the sustainability of the Transformation.
I play every class in every situation. I love them all.