The gamertag is bugged in both the main menu and in local worlds; It appears as "skinStandardCust" after importing a custom skin. It's worth noting that the gamerpic/xbox icon is also missing and defaults to a gray icon instead. Already tried logging out of everything and reinstalling to no avail. My tag obviously isn't "skinStandardCust".

Seems to not be bugged in realms and public servers but it's still annoying.