Update: Though it's difficult to confirm, it appears the glitch outlined in the below video is the result of a tool that lets you edit 3DS save files. It should not affect players who are playing Pokémon Sun & Moon normally, but it doesn't hurt to be safe.
Original story:
Pokémon Sun and Moon players have come across a glitch that is preventing them from progressing further in the game. Many players are currently reporting on Twitter that saving in either a Pokémon Center or the post-game Battle Tree has corrupted their files, causing the avatar to disappear.
No word yet on when a patch will be out, but we have reached out for comment. For the time being, it's probably wise to avoid saving your game in these locations.
Our Take
Hopefully this gets addressed soon. Pokémon is one of those games that you don't just play a little, so people could stand to lose hours of investment during their Thanksgiving break.