The code behind doesn't do much that would affect the rendering, other than centre the map on New York...
The Xaml contains a plain-blue canvas which behaves as expected (no RenderTransform is applied), and also the
<m:Map x:Name="viewMap" Width="751" Height="1000" >
<m:Map.Children>
<m:MapLayer>
<Canvas
Background="Blue"
Opacity="0.25"
m:MapLayer.MapRectangle="40.8325608405556,-74.1015908473376,40.5722860972124,-73.843755459154"></Canvas>
</m:MapLayer>
<m:MapLayer>
<Canvas
Background="Green"
Opacity="0.25"
m:MapLayer.MapRectangle="40.8325608405556,-74.1015908473376,40.5722860972124,-73.843755459154">
<Canvas.RenderTransform>
<TransformGroup>
<ScaleTransform ScaleX="1.245" ScaleY="1.245" />
<TranslateTransform X="-600" Y="340" />
<RotateTransform Angle="-60" CenterX="100" CenterY="100"/>
</TransformGroup>
</Canvas.RenderTransform>
</Canvas>
</m:MapLayer>
<m:MapLayer>
<!-- START m:MapLayer.MapRectangle="40.8031025373331,-74.1049947544734,40.5925255438291,-73.8190069004695"-->
<Canvas
m:MapLayer.MapRectangle="40.8325608405556,-74.1015908473376,40.5722860972124,-73.843755459154"
m:MapLayer.MapPositionMethod="Rectangle"
HorizontalAlignment="Stretch"
VerticalAlignment="Stretch">
<Canvas.RenderTransform>
<TransformGroup>
<ScaleTransform ScaleX="1.245" ScaleY="1.245" />
<TranslateTransform X="-600" Y="340" />
<RotateTransform Angle="-60" CenterX="100" CenterY="100"/>
</TransformGroup>
</Canvas.RenderTransform>
<Image RenderTransformOrigin="0.5,0.5" Stretch="Fill"
Width="751" Height="241" Opacity="0.25"
Canvas.Left="0" Canvas.Top="0"
Source="map.png"
x:Name="CourseMap">
<Image.RenderTransform>
<TransformGroup>
<ScaleTransform ScaleX="1" ScaleY="1"/>
<SkewTransform AngleX="0" AngleY="0"/>
<RotateTransform Angle="0"/>
<TranslateTransform X="0" Y="0"/>
</TransformGroup>
</Image.RenderTransform>
</Image>
<Path Stroke="Red" Opacity="0.25" StrokeThickness="10" x:Name="Course"
Canvas.Left="10.668" Canvas.Top="117.834"
Data="m5,5 L 40.2013036809816,33.2764570552147 66,54 78.0526953361599,54.3652331920048 82.5,54.5 87,46 117.348156182213,39.2559652928416 141,34 161.605413533835,37.6177443609023 206.076466165414,45.4256390977444 250.547518796993,53.2335338345865 272,57 295.37,57.2204716981132 325,57.5 330,52.5 334.866245587962,59.4069292216236 360.873304848597,96.3201746238157 361,96.5 393,78.5 395.646253021757,70.7266317485899 401,55 410,49 422.5,49 427.63885799036,49.9695958472377 449,54 450,50 454,51.5 462,57 465.491764705882,53.0094117647058 476,41 480,44.5 500.128407460545,31.6520803443329 503.5,29.5 512.5,28 509,24 523.5,19 531.5,19.5 532.448081264108,22.7234762979684 534,28 532.5,32 536,39 546.5,38.5 547.739871182215,21.4960523581966 550,-9.5 548.599535500995,-23.5046449900464 548.5,-24.5 545,-24.5 544,-18.5 578.550256996002,-17.5128498001142 579,-17.5 623.7,-17.1243697478992 668.85,-16.7449579831933 698,-16.5 712.001207000603,-8.77519613759809 712.5,-8.5 719.5,-8.5 720,-14.5 725,-14.5 728.5,-30.5 727.181190681622,-40.6108714408974 727,-42 724,-44.5 695.5,-45.5 695,-49.5 687.71,-49.5 687,-49.5 686,-46.5 644.72,-46.156 626,-46 608.5,-49 603,-54 601.760854583046,-53.9572708476912 588.5,-53.5 586,-51 582.5,-53.5 560.5,-54 558.675856929955,-53.0879284649777 548.5,-48 548,-70.5 559.097981290005,-68.5578532742491 568,-67 " />
<Ellipse RenderTransformOrigin="0.5,0.5" Fill="#FFff0000" Stroke="#FFff0000" x:Name="marilsongomesdossantosnewyorkmarathon" Width="11" Height="11" Canvas.Left="10.668" Canvas.Top="117.834">
<Ellipse.RenderTransform>
<TransformGroup x:Name="TGmarilsongomesdossantosnewyorkmarathon">
<ScaleTransform ScaleX="1" ScaleY="1" x:Name="RST_marilsongomesdossantosnewyorkmarathon" />
<SkewTransform AngleX="0" AngleY="0" />
<RotateTransform Angle="0" />
<TranslateTransform X="0" Y="0" x:Name="TTmarilsongomesdossantosnewyorkmarathon" />
</TransformGroup>
</Ellipse.RenderTransform>
</Ellipse>
<Ellipse RenderTransformOrigin="0.5,0.5" Fill="#FF00ff00" Stroke="#FF00ff00" x:Name="toddpricenewyorkmarathon" Width="11" Height="11" Canvas.Left="10.668" Canvas.Top="117.834">
<Ellipse.RenderTransform>
<TransformGroup x:Name="TGtoddpricenewyorkmarathon">
<ScaleTransform ScaleX="1" ScaleY="1" x:Name="RST_toddpricenewyorkmarathon" />
<SkewTransform AngleX="0" AngleY="0" />
<RotateTransform Angle="0" />
<TranslateTransform X="0" Y="0" x:Name="TTtoddpricenewyorkmarathon" />
</TransformGroup>
</Ellipse.RenderTransform>
</Ellipse>
<Ellipse RenderTransformOrigin="0.5,0.5" Fill="#FF0000ff" Stroke="#FF0000ff" x:Name="craigdunnnewyorkmarathon" Width="11" Height="11" Canvas.Left="10.668" Canvas.Top="117.834">
<Ellipse.RenderTransform>
<TransformGroup x:Name="TGcraigdunnnewyorkmarathon">
<ScaleTransform ScaleX="1" ScaleY="1" x:Name="RST_craigdunnnewyorkmarathon" />
<SkewTransform AngleX="0" AngleY="0" />
<RotateTransform Angle="0" />
<TranslateTransform X="0" Y="0" x:Name="TTcraigdunnnewyorkmarathon" />
</TransformGroup>
</Ellipse.RenderTransform>
</Ellipse>
<Ellipse RenderTransformOrigin="0.5,0.5" Fill="#FFdd00aa" Stroke="#FFdd00aa" x:Name="lancearmstrongnewyorkmarathon" Width="11" Height="11" Canvas.Left="10.668" Canvas.Top="117.834">
<Ellipse.RenderTransform>
<TransformGroup x:Name="TGlancearmstrongnewyorkmarathon">
<ScaleTransform ScaleX="1" ScaleY="1" x:Name="RST_lancearmstrongnewyorkmarathon" />
<SkewTransform AngleX="0" AngleY="0" />
<RotateTransform Angle="0" />
<TranslateTransform X="0" Y="0" x:Name="TTlancearmstrongnewyorkmarathon" />
</TransformGroup>
</Ellipse.RenderTransform>
</Ellipse>
</Canvas>
<!-- END -->
</m:MapLayer>
</m:Map.Children>
</m:Map>
</Canvas>
For reference...