Keep getting Assertion failed: Blueprint->GeneratedClass != nullptr

So I’m working on a project using the Gameplay Ability system and I exposed a TSubclassOf as a UPROPERTY, and now everytime I compile my code, the editor crashes with this error:

Assertion failed: Blueprint->GeneratedClass != nullptr [File:D:\Build\++UE4+Release-4.17+Compile\Sync\Engine\Source\Editor\UnrealEd\Private\Kismet2\BlueprintEditorUtils.cpp]

Any ideas? I have no idea why it’s doing that.