Like the topic says. There's a question mark in one of my slots.
When I go to my party through the main menu, there's an empty spot. However, when I try and withdraw one from storage into the party, it says my party's full. I look at it through the "party pokemon" button at the bottom and there it is.
What's going on?! It's strange. I've never had this problem before now. Luckily, I have a save from before this started occurring. But now I'm back one gym..