Yeah, that happened to me, on a mule just the other day! :O I had no idea what was going on.
Are the devs working on something in the items system that I missed a notif for somehow?
It is an unfortunate glitch that has been affecting random users for nearly a year now. It usually happens after you edit your wishlist. There is no way to restore it. You can re-add everything but there is a chance it could happen again so I would suggest saving it to your computer, just in case.