Can you check if your SwiftData properties have default values, and if so, remove them and just set them from init? So if you have a property called var creationDate: Date = Date() change to var creationDate: Date, and in init() set the date to Date(). Let me know the result, I'm curious!

Sounds like my issue, and found that this problem can occur after you've upgraded your macOS beta. I know this because I had a working app on a previous Xcode beta, and it was only until I updated my macOS beta that this problem occurred. See my issue here: [(https://developer.apple.com/forums/thread/734970)]