CloudKit stopped syncing on WatchOS

Hey,

I have an iOS/watchOS application that has been in the App Store since the beginning of last year (for reference: https://endsplus.com). Part of the functionality includes:

Create a Fixture on the Phone

1. Create Fixture on iOs
2. Fixture is saved to Core Data
3. Core Data syncs with CloudKit
4. WatchOs pulls down the record, updating a table of the same name
5. I can show the Fixtures on the Watch.

Track a game on the Watch and then save it.

1. Create a Game on WatchOS
2. Game is saved to Core Data
3. Core Data syncs with CloudKit
4. iOS pulls down the record, updating a table of the same name
5. I can show the games on the phone.

For reasons I am unable to work out syncing of core data tables between the phone and the watch has stopped working.

I know that the iOS coredata/cloudkit functionality is working as I can create a record on my physical phone, then run a simulator and log in with the same iCloud account and see the record.

But the functionality has stopped working for watchOS. I have added a new table to the Watch side that is not syncing to the Phone, but an existing table (Fixture) that has been working has also stopped syncing between the phone and the watch.

None of my Persistence/Core Data code has changed. My new table is associated with a Cloud Store, the same as my old table is.

What options are they available to me to try and debug this. The watchOs simulator doesn't seem to work with CloudKit, telling me it is not signed in.

I've tried looking at the CloudKit database logs, but obviously for security I can't see the data, but I can't see any errors from the watch.

I've uninstalled and re-installed the application (on the phone and the watch) numerous times, but that isn't working.

Does anyone have any ideas?

Thanks