I have a CoreData-based app where I am experimenting with inter-device synchronization using iCloudKit. At the moment, I am running in Development mode and am using an iPad and a MacCatalyst app as the two test devices. Bottom line - things aren't working. Looking at the generated logs, it appears that after getting everything set up, data requests are being cancelled because of pending requests. (I.e., it looks like a request is being LOST or maybe being UNANSWERED).

Both the Mac and the iPad use the same AppleID (but not the AppleID associated with the application).

I have put together a folder that may help explain the problem. It contains the code of my CoreDataStack class, the SceneDelegate that makes the call to open the database, the Xcode logs (from both the iPad and the iMac runs) showing the progression of messages, and printed images of information from my iCloudKit Dashboard.
(in case the folder attachment doesn't work, try this Dropbox download: https://www.dropbox.com/sh/vdeg9pcmy2fdo17/AABNuCdojZjr5tP6BEpu3T0ma?dl=0 ).