After sharing the records through iCloud, when I run the app on Xcode I can see them, but when I run it either on TestFlight or from App Store it doesn't work. The shared records aren't fetched. This has been going on for months.
Shared Records don't appear when app is in Production
Perhaps you didn't set up subscriptions in Production? You might have set them up in Development, then neglected to do in Production as well.
When you say "it doesn't work", can you clarify what exactly you're doing, what you're expecting to see, and what you are seeing instead?
When Alice and Bob are sharing a record and Alice changes something in that share, Bob will only see the change automatically if there's a subscription set up for it. If you are expecting a notification about the change, and you're seeing it work in Development but not in Production, verify that you have in fact established a subscription in Production.
If, on the other hand, you are attempting to fetch a shared record with what should be a reliable recordID and this works in Development but not in Production, then it might be something else.
Just to explain even further: the Private Records are always fetched, both in Xcode and in TestFlight/App Store, while the Shared Records, get only fetched in the Xcode version but never in Production (TestFlight/App Store). I've experienced this issue since they worked on iCloud with the new iOS15.
Still no answer from the Feedback Assistant and the issue is still persistent.