Has this happened to anyone else? I had about eight werewolf perks, then just now I got one more and when I opened the perk tree to spend it the rest were all gone.

Is there something that I've done that has triggered that so I can avoid it in future?

Never heard of this one before. What platform are you on? Obvious Q : Have you rebooted and tried using an earlier save?

did you redownload DG or anything like that?

This is probably what happened.