Comment 3 for bug 1728183

The rectangleGeometry element requires relative coordinates, and we give it an absolute position. So the clipping object exists, but is not correctly set.

In your example, replacing:
      <RectangleGeometry xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" x:Key="clipPath2183" Rect="33, -27, 115, 63 "/>
with:
      <RectangleGeometry xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" x:Key="clipPath2183" Rect="108, 21, 115, 63"/>
fixes the issue.

But now we need to find an elegant way to fix it in the XSLT file.