Hey, I reinstalled macOS again because I had to work and was feeling hopeless. I will highlight this on my Twitter and mark your answer as solution to indicate this is what I'll try next time it happens.

Was hoping I wouldn't have to actually move all that logic back into the App target, even though that does make my project compiling again. Thanks for the mention, anyway!

Could you show me what that code looks like? I have a List of Characters that have builds, I want to move builds to another character if needed. I have a draggable modifier on the build, and a destination on the character, but it doesn't do anything :')