On iOS 15.2, how do I load a cloudKit public container with user not logged in to iCloud

I am using the following to initialize my PersistenCloudKitContainer with the goal of loading a shared poblic cloudKit database:

container = NSPersistentCloudKitContainer(name: "FaceExplorer")
     
    guard let description = container.persistentStoreDescriptions.first else {
       print("Can't set description")
       fatalError("Error")
     }
       
    //ios 14 bug fix https://developer.apple.com/forums/thread/682925
    description.cloudKitContainerOptions?.setValue(1, forKey: "databaseScope")
// "normal" / ios 15 version description.cloudKitContainerOptions?.databaseScope = .public
     
    //seems to work & Load on iOS14.5
    description.cloudKitContainerOptions?.setValue("iCloud.com.myDomain.myContainerID", forKey: "containerIdentifier")

container.loadPersistentStores(completionHandler: { (storeDescription, error) in 
...

This all works great on iOS14 and also loads on iOS15.0 - 15.2 with users logged into iCloud with the iCloud drive option checked.

However, when the iCloud drive option is not checked on iOS15 only, the container will not load.

Please help me figure out what I might be missing or doing wrong. Thanks