I've entered some code on Version 4.5.1 of Playgrounds on my iPad mini running iOS 18.1.1. The file is saved on iCloud and so is available on my Mac running OS 15.2. However, the file will not open in either Playgrounds v 4.5.1 on the Mac (error "Unable to get file wrapper for contents.xcplayground.") or Xcode 16.1 (error "Couldn't load settings from contents.xcplayground"). The file's type is .playgorund. Any thoughts?