"Platform implementation is not referenced" on UWP

[rcoodey]

The sample runs fine for Android but whenever launching the UWP get the exception: "Platform implementation is not referenced". This happens in this line of code:
async void StartUrhoApp() { urhoApp = await urhoSurface.Show<UrhoApp>(new ApplicationOptions(assetsFolder: null) { Orientation = ApplicationOptions.OrientationType.LandscapeAndPortrait }); }
Got Xamarin.Forms at 2.3.0.107 and UrhoSharp.Forms at 1.0.557. Also tried Xamarin.Forms at 2.2.0.31 like the sample.