I have an application with targets on iOS and macOS that uses CKSharing in one feature. It wokrs fine for the iOS targets but not macOS. When I try to accept the share (I tried generating the share from an iOS device and another Mac) it shows an alert telling me I need to update to the latest App Store version before I can accept. All of the other CloudKit features work fine on both platforms; just can't accept the CKShare except on iOS.
Can't accept CKShare on Mac (macOS 10.13)
Could you get this written up in a bug report for us? If you can include iCloud Drive & CloudKit logs that would be great: https://developer.apple.com/bug-reporting/profiles-and-logs/?name=cloudkit