I was exploring the beta of xbox one minecraft. Then I exited the beta by uninstalilng minecraft and then reinstalling it. Then when my brother tried to get into the same world that I play on as a guest, his account was gone. It put him back at the world spawn with no experience and no anything exept an empty map. This is annoying because we were building a city and 3 stacks of terracotta and a stack of powered rails were gone with his character along with his all mending, unbreaking gear. All his gear was the best in the game too. All his builds are still in the world.