Ever since Pokémon GO developer Niantic released new avatar items in the in-game shop, the immensely-popular mobile game hasn’t been running properly for some users. A number of players are reporting longer-than-usual loading times, Pokémon GO Gyms won’t load and Raid Battles are met with various errors. Niantic has yet to address these issues, but stay tuned for any updates.
Source: The Silph Road on Reddit