Camera Depth fade on WPO works on geometry but is broken on virtual shadow maps?

i am using camera depth fade in a material to make WPO fade away. the object is a waving wire… the shadow is made by a directional light. So when i back away from the wire lookign at it with the directional light to my back… the wire and the shadow it casts fade the WPO away correctly. But if i float my camera to the other side and look toward the directional light… the WPO fade works on teh geometry but the shadow continues to move even though the geometry stopped moving… why?