I was starting up minecraft on a vpn to play (it's the only way multiplayer works for me) and it was stuck on the loading screen for 10 minutes. It turned out my vpn connection had timed out so I closed minecraft and restarted my wifi network without the vpn. When minecraft finally opened my characters were Steve and Alex. Only one custom character was still there. It was probably my fault on closing the game while it was loading but I still wanted to inform anyone