Xamarin.Forms.Picker Class Causes App Crash on Android

We took the C# Picker class example from https://developer.xamarin.com/api/type/Xamarin.Forms.Picker/ and are experiencing a crash on Android (Kitkat and Lollipop builds) - This works fine on IOS

To reproduce the crash, in the picker UI if you hold on the item above or below the selected item you get an UnhandledException. Here is the stack trace:
An unhandled exception occured.

09-30 10:51:52.866 E/AndroidRuntime(24505): FATAL EXCEPTION: main
09-30 10:51:52.866 E/AndroidRuntime(24505): Process: PickerTestXam.Droid, PID: 24505
09-30 10:51:52.866 E/AndroidRuntime(24505): java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.widget.ImageButton.isShown()' on a null object reference
09-30 10:51:52.866 E/AndroidRuntime(24505): at android.widget.NumberPicker$ChangeCurrentByOneFromLongPressCommand.run(NumberPicker.java:2267)
09-30 10:51:52.866 E/AndroidRuntime(24505): at android.os.Handler.handleCallback(Handler.java:739)
09-30 10:51:52.866 E/AndroidRuntime(24505): at android.os.Handler.dispatchMessage(Handler.java:95)
09-30 10:51:52.866 E/AndroidRuntime(24505): at android.os.Looper.loop(Looper.java:145)
09-30 10:51:52.866 E/AndroidRuntime(24505): at android.app.ActivityThread.main(ActivityThread.java:5972)
09-30 10:51:52.866 E/AndroidRuntime(24505): at java.lang.reflect.Method.invoke(Native Method)
09-30 10:51:52.866 E/AndroidRuntime(24505): at java.lang.reflect.Method.invoke(Method.java:372)
09-30 10:51:52.866 E/AndroidRuntime(24505): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399)
09-30 10:51:52.866 E/AndroidRuntime(24505): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194)

We are using Xamarin Forms v1.5

Any help is appreciated

Thanks,
Alan