Ideas
Me too it exclusively happens with werewolves too!
I tried to limit werewolves to Moonwood Mill through the Pack Settings, but it doesn't prevent the bug. They still come and get stuck. So it doesn't matter if they are in their human or beast form, but something in the code of the werewolf make them act differently than other sims at the time of business closure.
The easiest method really would be to just give the players some agency over werewolves. We can turn on the "no trespassing" for vampires. With ghosts they gave us the "no ghost" sign. We just need a silver bullet (so to speak.) Honestly, giving the player a method to calm werewolves would solve a bug which is werewolves getting stuck in werewolf form. Just make something that sims can purchase and throw at a werewolf to "calm" them and revert them back to human form. Silver glitter party popper.