Collecting new fairies in Hyrule Warriors Legends

I recently started playing Hyrule Warriors Legends for the first time. When I first launched the game, it downloaded a bunch of updates and then bombarded me with a massive list of rewards that went with the updates (e.g. 6 million rupees, 6 fairies, tons of food, etc).

The game lets you collect fairies in the Adventure mode. Or at least, it's supposed to. However, when I collect a fairy in Adventure mode (by capturing the keep that holds the fairy, walking over the fairy, and getting a message that I've collected a new fairy), nothing happens at the end of the mission related to the fairy, and no new fairies are added to my inventory.

This wiki page says that you can only hold a maximum of 3 fairies, but that maximum can increase by completing Adventure Mode maps. Since I already have 6 fairies, I assume the maximum is at least 6. The page also says that when you collect a new fairy, the game will ask whether you want to get rid of a previous fairy. However, I've never seen such a dialog. I started the game with two water fairies and two light fairies, so I'd like to get rid of the duplicates, but can't figure out any way to dismiss fairies and don't seem to be given the opportunity after "collecting" new fairies.

Am I misunderstanding something about the fairy system? How come nothing happens when I collect a new fairy?