The app crashes on the new release on TestFlight.

Do your package support lazy loading @Chuck H ?

If SwiftData models are not sendable then shouldn't Xcode/Swift raise an error?

Nullable solved the issue! I have file a report here with ID FB15169265. https://feedbackassistant.apple.com/feedback/15169265

It seems to work! But are you saying that non-optional relationships do not work as intended in SwiftData?