I'm a first time developer, relying heavily on Claude Agent. In my app, I'm using CloudKit to sync data between devices, but after a migration something got corrupted and syncing is no longer working.
I'm using SwiftData with NSPersistentCloudKitContainer. I'm using Xcode 26.4.1 on a Mac mini. I'm testing my app on the same Mac mini, running Tahoe 26.4.1 as well as an iPad 12.9 running iPadOS 26.3.1 and an iPhone running iOS 18.7.8.
Sync stopped after a cachedTotal property was added to a SwiftData model, which triggered a backfill migration that wrote to all records simultaneously across multiple devices. This was followed by an iCloud sign-out/sign-in on the Mac.
Here’s a summary of everything I’ve tried already:
- Reset All Data on all devices multiple times
- Deleted and reinstalled the app on all devices
- Deleted the CloudKit zone twice
- Force-deleted local SQLite store files to clear change tokens
- Zone and subscription both appear correct in the dashboard
- Change token updates when data is written (confirming uploads work)
- No data propagates to other devices in any direction
Uploads appear to succeed (change token changes) but imports never fire on any device. In other words, writes work, reads don’t.
Is there a way to fully reset the CloudKit container's production private database for a TestFlight app, or is there a way to diagnose why imports are not firing despite a valid zone and subscription?