PanGestureRecognizer not working in Android (Xamarin Forms)

I recently created a custom control that contains two child controls within a Grid. I added a PanGestureRecognizer to the custom control to move the child controls through the Y axis when the PanUpdated event fires. This works fine in iOS, but Android does not fire the PanUpdated event.

To investigate I looked at the example of how to do pan gestures here: https://developer.xamarin.com/guides/xamarin-forms/user-interface/gestures/pan/

This example works on Android, but as soon as you change the Image inside the PanContainer to something else, say a Grid containing some other controls, then PanUpdated stops firing. As I mentioned this all works well on iOS.

I'm currently using XF 2.3.3.180

Can anyone offer any help or guidance on how to get the pan gesture working in Android?