FClassFinder can't find blueprint of derived game state

Hello! I’m currently trying to set the default game state in a game mode. What I’m trying to do is have a C++ class derived from AGameState, then set a blueprint derived from that class as the default game state. I’ve gotten it to work with just the C++ class and with a blueprint derived from the original game state, but I can’t get it to work with the blueprint derived from my custom class.
When I start the unreal editor using a blueprint derived from my custom class it gives me this error: “Default Property warnings and errors: Error: CDO Constructor (RPGGameMode): Failed to find /Game/ThirdPerson/Blueprints/BPGameState.BPGameState_C”

Here’s my code: Excerpt from MyGameMode.cpp - Pastebin.com

I’ve tried this using both AGameMode and my custom class in the template and neither work. Any ideas on how I should go from here?