I am seeing the same thing but not related to MDM. I want messages to sign into icloud on a VM. On a macos 26 VM this works perfectly. On macos 27 (latest prod) it fails due to the same error above. Steps to reproduce Create a macOS 27 VM using UTM 5.0.8. Sign into an Apple Account. Open Messages and attempt to activate iMessage. Open Messages → Settings → iMessage. Expected result iMessage activates successfully, displaying the registered email address under “You can be reached for messages at”. Actual result iMessage does not activate. No registered addresses appear. Messages stored in iCloud are not displayed. The VM does not appear as an available device for SMS forwarding. FaceTime launches but does not display its interface.

This seems to also be preventing syncing of Passwords.app inc shared passwords.