I just had this issue yesterday where my werewolf Sim wouldn't transform, regardless of way forced to. Whenever I try to transform her, the game just automatically cancels it. Even the game tried to transform her when night started, but had no luck either. I even dragged her needs down to force her to, but that didn't work either... does anyone know how to solve this? My other werewolves transform just fine.

I had a similar problem with a fairy once. Turned out she was a fairy in looks, but the game didn't recognize her as a fairy, so she didn't have any fairy powers.

I think I fixed it by turning her to human and back again to fairy.

Ok.... can I also cure the werewolf and make her one again?

My guess is that her werewolf shape (special outfit) is broken.
So, yes, turning her into a human and then back into a werewolf might fix her. You will have to design her werewolf features again, though, but as they seem to be broken anyway you'd have had to do that again one way or another.

If you use MasterController you could also try editing her in MC's CAS; maybe that'll regenerate her werewolf shape.

Thanks. Now I'm wondering how the werewolf shape could break..

I had plenty enough problems with TS3, so it's probably just another bug in the system.