Thanks for the suggestions. Fortunately I have the concurrency debugging working in my main application targets for both platforms and my entire Core Data stack is in a shared framework between them all, so it makes it easier to rule out some potential issues. I've checked all of these suggestions and none of them resolve the issue for me. Have you had this feature work for you in any kind of application extension - I haven't been able to find out if this feature works at all in extensions.