I had the same issue and managed to fix it after finding out more about what's causing the issue here: https://github.com/AudioKit/AudioKit/issues/2279#issuecomment-705285458 TLDR For completeness, the issues were that some file names were colliding with each other. In my case it was because of a Core Data model file. If that's the problem in your case too then read my answer from here: https://developer.apple.com/forums/thread/657896?answerId=639959022#639959022

I had the same issue and managed to fix it after finding out more about what's causing the issue here: https://github.com/AudioKit/AudioKit/issues/2279#issuecomment-705285458 So my problem was that I had the Core Data model files (.xcdatamodeld directory and the .xcdatamodel file within that directory) called after the package name but I also had the main source file called the same as the package name (eg: MyPackageName.xcdatamodel and MyPackageName.swift), and the fix was to rename the Core Data model files (.xcdatamodeld directory and the .xcdatamodel file within that directory) to Model.xcdatamodeld and Model.xcdatamodel and that was it.