Just for future reference, the minimum supporting AppStorage inside ObservableObjects is iOS 14.5 (https://developer.apple.com/documentation/ios-ipados-release-notes/ios-ipados-14_5-release-notes)

Thank you for the suggestion! I tried to take a step back with a brand new container and simply specifying it; this is what I get as an error: Unresolved error loading container Error Domain=NSCocoaErrorDomain Code=134060 "A Core Data error occurred." UserInfo={NSLocalizedFailureReason=Unable to find a configuration named 'default' in the specified managed object model.} This happens when there is no name specified in the ModelConfiguration. The model seems fine in terms of CK limits.

Ziqiao, thank you so much for this! I can confirm that removing the migrations makes it work. It seems I don't even need to create 2 containers, just by removing the migrationPlan: parameter SwiftData is able to migrate the app model in production to the CloudKit compatible one. I will try to reproduce on the new betas later today. Thanks again and happy wwdc24! Best, Matteo