First, it would be great if you allowed for users not using PTC to be change their account e-mail. Many students used their college email, which are set to expire in the near future. A one time change would help these users keep their accounts and progress.
Also theres been lots of errors at the Gym where the Pokémon disappears, or where it still takes significant damage after dodging an attack.
Last, the bug where the Pokémon in the screen randomly disappear, along with those in the nearby/sightings list. It comes back after a while, but it happens enough that it gets in the way when Im about to click on a Pokémon.
Persey Stella about Pokémon GO, v1.31.0