Minimal example that should load Geotiffs with ArcGIS runtime version 100

MainWindow.xaml.cs

using System.Threading.Tasks;
using System.Windows;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.LocalServices;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Rasters;
using Esri.ArcGISRuntime.Symbology;

namespace ArcGISMinimal
{
    public partial class MainWindow : Window
    {
        public readonly SpatialReference SpatialRef = new SpatialReference(4326 /* WGS84 */);

        public MainWindow()
        {
            InitializeComponent();

            m_MapView.Map = new Map(SpatialRef)
            {
                InitialViewpoint = new Viewpoint(new MapPoint(11.576, 48.137, SpatialRef), 0.1)
            };

            Task.Run(async () =>
            {
                Layer l = null;

                // This works...
                {
                    //var localMap = new LocalMapService("C:/arcgis_maps/Test.mpk");
                    //await localMap.StartAsync();
                    //l = new ArcGISMapImageLayer(localMap.Url);
                }

                // This doesn't work
                // Image is from: http://eoimages.gsfc.nasa.gov/images/imagerecords/57000/57752/land_shallow_topo_2048.tif
                {
                    var myRaster = new Raster("C:/arcgis_maps/land_shallow_topo_2048.tif");
                    await myRaster.LoadAsync();
                    l = new RasterLayer(myRaster);
                }

                m_MapView.Dispatcher.Invoke(() => m_MapView.Map.OperationalLayers.Add(l));
                await l.LoadAsync();
                await m_MapView.Dispatcher.InvokeAsync(async () => await m_MapView.SetViewpointScaleAsync(750 * 1000));
            });
        }
    }
}