I was going to suggest all the restarting process but some people already mentioned it. Did you tryed to go back to Metahuman Creator, make a small adjustment and then return to check if it is avaiable?
Another point that already happened to me…more than one account lol
Yes, I already created a Metahuman in an account and then in the bridge I was logged in another account. When I discovered that this was the answer I felt so stupid hahaha
Hope that helps