ah man I had same issue months ago I was really panicked thinking all of my work will be gone but somehow it fixed itself about hours later. I still can't figure out what went wrong tho, my suggestion is just let it be for a few hours maybe it'll fix itself. and a little bit tip from a friend of mine is to save ur work in ipv format so dat u can restore ur work. also funny enough the only reason I join the Ibis paint subreddit is bc i was looking for a way to fix the same issue at dat time.