Ideas
I am having the same issue and was referred to this thread. I changed a werewolf Sim from the gallery to human in CAS, and shortly after I started playing, my human Sim went a werewolf rampage and died of a cardiac explosion because of the rampage. And the entire time they were "rampaging," my Sim was stuck in the same transformation animation loop, except they never changed into their werewolf form. They just kept going through the animation over and over again, and since I couldn't even click on the sim because they were rampaging, I couldn't stop them from rampaging. I just had to wait it out. I've tried removing my Sim's werewolf traits using the Cheat Sim Info --> Remove Traits. I also tried traits.remove_trait trait_occultwerewolf. However, my Sim's ghost still runs around like a rampaging werewolf and randomly starts howling, so neither of those fixed the issue. I also tried to de-age the character, but even as an infant and toddler they were getting werewolf moodlets that were for teenage and adult werewolfs and the infant hardcore glitched when that happened. Their body elongated and it was really weird. I used MC Command to remove all buffs from the sim and that has seemed to help thus far, but i don't know if it's fixed the issue or not. I'm afraid to return my now ghost sim back into their human form and risk them getting stuck in a rampaging loop and dying again.