That's a real shame. Obviously inheritance is a key advantage of OOP. There have been few if any true object databases. Realm was looking good for a while, but Mongo bought them, then dropped support leaving all their users/customers out in the cold. I had great hopes for SwiftData's support for inheritance, but if you can only use it locally, not too useful after all.

Yes, my architecture for an upcoming app uses inheritance with SwiftData, but I will need CloudKit, so this bug means I will need to figure out a different architecture, unless it's fixed soon.

I have a class that is not part of the UI in which I use with SwiftData. For the fetch method, I pass in the model context and use modelContext.fetch(fetchDescriptor). I also pass in the modelContext to the save method and just use do/try/catch for the insert/update/save calls as I would in a View. It all works fine.