Map snapshot in WidgetKit does not call the completionHandler callback of `MKMapSnapshotter.start`

I've tried MKMapSnapshotter in the TimelineProvider , but the completion handler of the start is never called (snapshot is a MKMapSnapshotter object and I have verified that the callback is called when this code runs on the actual app and not the widget TimelineProvider. What am I missing?

Code Block          
    snapshot.start { (snapshot, error) in
      let image = Image(uiImage: snapshot?.image)
      completionHandler(image)
    }