In the new GDK version, world's can save in multiple different locations, and if there is a sign-in issue, it uses the wrong folder. There should be a folder in the gdk installation called “users” (or similar) with folders in there being “Shared” or a random string of numbers. Check every subfolder in the users directory. If the world's are not there, it's likely that your worlds were deleted along with the game.
Sam Ash
In the new GDK version, world's can save in multiple different locations, and if there is a sign-in issue, it uses the wrong folder. There should be a folder in the gdk installation called “users” (or similar) with folders in there being “Shared” or a random string of numbers. Check every subfolder in the users directory. If the world's are not there, it's likely that your worlds were deleted along with the game.