Is there a bug in WinPhone (WinRT) - SearchBar?

I have a SearchBar defined in Xaml:

In Android and Win Desktop the SearchText is correctly bound.

In WinPhone (WinRT) SearchText is an empty string.

Since the binding is working correctly in Android and Win Desktop, I suspect this is a bug in Xamarin forms. Can anyone confirm that/ has anyone successfully bound to a SearchBar in the new Windows Phone Xamarin.Forms?

Thanks,