I have read and tried all the possible solutions available online, but still didn't get a result. My multi-platform iOS/macOS app uses private databases in iCloud with Core Data. All works as expected when I build the app from Xcode to my multiple devices: data is being synced. But when I upload the app to TestFlight, data is not being synced. This is what I have already tried: In CloudKit Dashboard, I reset the schema and deployed schema changes from the development to production. In Xcode project settings, in Targets, under Frameworks, Libraries... I added the CloudKit.framework, set as "do not embed". In Xcode project settings, under Signing & Capabilities, all the CloudKit, Background fetch and Remote notifications checkboxes are enabled for both Debug and Release. They all point to the same correct iCloud container. In Xcode project settings, under Build Settings, Code Signing Entitlements for both Debug and Release point to the same entitlements file. In .entitlements file, CloudKit container identifier points to the correct container. iCloud Services set to CloudKit. In .entitlements file, APS Environment for both iOS and macOS is set as "production". In Core Data .xcdatamodeld file, under Configurations, I have a Default option, and it is being set to "Used with CloudKit." Each time I upload new version to the TestFlight, I delete all the previous versions from all my devices, so development and production containers are not mixed up in any way. I understand that I may be missing something. But after researching all the resources available online, I didn't find anything else to configure or to add in this setup. I want to point out again that data is not being synced only in TestFlight, and thus, possibly, after release. Whenever I build app directly to the device from Xcode, all works as expected. I hope someone can help me.