@talking_small - Thanks for the offer, but I did submit what they asked for here to the Feedback report, but nobody has replied to that Feedback at all and no requests have been asked there... I'm still waiting for ANYONE from Apple to reply! Sadly, I don't have the time (nor ability) to implement my own syncing solution, so basically Apple breaking NSPersistentCloudKitContainer has broken my app... and that is really disappointing. I might have to stop offering the iPad & Mac versions now.
@Alex_Vorobiev - My Development & Production Environments have not changed and are all in sync, with no missing fields - and my App Store app syncs fine on iOS 14 devices. Any devices running iOS 15 see it fail. I'm not even talking about the failures I'm seeing building an App in Xcode - this is with my current in-the-wild App that has been unchanged for several months. My database is 'complex' but that was the whole point of NSPersistentCloudKitContainer - to sync a Core Data store. If it can't do that properly, then they shouldn't offer it at all. It's always worked fine though with my data... except since iOS 15 beta 4. Apple definitely broke something. I've now submitted a TSI as Apple has released the RC version of iOS15 as I feel this is the only way anyone from Apple will communicate with me about this...