"Syncing User Data" Does Not Work

When I start Minecraft, after going through a loading screen, it takes me to a screen that says "Loading user data This may take a few moments." No matter how long I wait it never finishes, and if you hit "cancel" the game freezes. The only way I can get into Minecraft is if I sign out of my profile, load the game, sign back in, and then hit cancel. (It also indefinitely syncs on this page, so you have to cancel)