This has ben a problem for me in the past. I open my survival world and all my items are gone, it thinks I'm a new User on the world. I am logged in to the Same account on Xbox Live and it still keeps doing this. I had VERY OP Netherite and I keep losing it. Luckly I learned from the last time this happened and have a exported backup of my world but this is frustrating becuase I lost alot of progress though. Please don't mark this as a Duplicate because I know others may likely have this problem but this has ben a issue for A WHILE. Please fix it