I've had that same issue and you have to let it auto save first then you should be able to save!

im having the same issue. whenever i turn any one of my followers into a werewolf, after they first turn and then trun werewolf for first time and back to human form. it crashes. do i just wait for auto save to kick in because i tried to save onetime and it crashed. and another time when i tried to forward time it crashed as well. any adive on this

Well I've found that to have this working properly you shouldn't talk to your follower afterwards until you're at least gone through one loading screen which ususally is when the autosave kicks in though it crashes if you do try to save normally, it's a little weird though it might be different for you, but I've usually found that if you do it in an area where there isn't anyone fighting and if you don't look at your follower after turning them it shouldn't crash, also if your're conserned about having it happen in the middle of cities, don't worry any follower who gets turned into an Werewolf or Vampire in an city won't cause you to get attacked they're kind of invisible to the guards or something!

force an autosave and reload cleared all issues on this for me. can even save with followers in werewolf form now with no crash