"Favorite" Glitch

When I send a Pokemon to a gym who is a marked as a favorite Pokemon, the favorite icon is deselected as soon as you click on that Pokemon. It doesnt let me mark it as a favorite again until it returns from a gym. With some of the Pokemon Ive invested lots of dust into, I now fear I might delete them by mistake, or from having the app open in pocket. The game didnt used to do this, this is a problem Ive been dealing with for the last few weeks.

Shinolavol1 about Pokémon GO, v1.39.1