Can I check a) You saw my comment with the Feedback report ID - https://feedbackassistant.apple.com/feedback/15590237 b) Now that this has migrated from a technical support request to a forum post to a feedback report, is there any point waiting for a response on this, or should I work under the assumption that it's a bug, and won't be fixed anytime soon?

The playground has let view = ContentView() .environment(\.managedObjectContext, stack.view) Note stack.view not stack.main. I constructed a test Xcode project as per your instructions (but using the view MOC) and got the same results as in the playground.

Just hit this error. I rerun the latest-but-one build on our build server and submitted it. It went through fine. So I reran the latest build (i.e the git hash that failed the first time round) and submitted it. It went though fine....