My sugar glider, buttercup, has always had a normal length tail. Now her tail is about half that length! I cant find any fur in the cage or anything, and she does not appear to be in pain. She's eating normally and is moving around normally as well. Has anyone had this problem?

Good morning!
I noticed nobody has been able to answer yet.
I haven't had it happen to me, but I have read about gliders getting tail injuries and/or self-mutilating for a variety of reasons.
It's been a few days since your post so I don't know if you've found anything in the cage or taken her to the vet yet. If you haven't gone to the vet, that's definitely my recommendation. I would also ask if you could take pictures of your cage setup, including the wheel, so maybe our members here can take a look to see if anything stands out to them as potentially dangerous.

Keep us updated! I hope Buttercup is ok.