The solution to my problem was to NOT store all my projects in iCloud Drive. I used to store them in my Documents folder, but that's synced to iCloud. I now have a Developer folder right next to my applications and stuff: ~/franksolleveld/Developer/all-my-projects

@Model public class Feeling { public let id: UUID public var afraid: Int public var angry: Int public var sad: Int public var ashamed: Int public var happy: Int public var neutral: Int public init(afraid: Int, angry: Int, sad: Int, ashamed: Int, happy: Int, neutral: Int) { self.id = UUID() self.afraid = afraid self.angry = angry self.sad = sad self.ashamed = ashamed self.happy = happy self.neutral = neutral } } This is the Model Feeling that is causing issues apparently

Also cleared DerivedData and made sure Feeling is a Model.

Hey, Developer Mode is available from iOS 16. You could install a beta of iOS 16 and try it or wait until the public release later this Fall. Frank.