Shadow moves with camera tracking

If the camera track is accurate and you set the origin and ground plane, then add the camera and a solid using the same target, then you establish and verify the position of the surface where you put the 3D layer that you want to cast a shadow, everything should work out. 

The proper workflow for setting a light would be to Shift + Parent the light to the shadow-casting 3D layer, then back the light away from the layer casting the shadow and tie the Point Of Interest for the light to the position of the layer casting the shadow. This is very easy to do with a simple pickwhip expression. The next step would be to position the light to cast the shadow you want. If the footage was snot in sunlight, then you will be better off using a Parallel light than a Spotlight. Everything should line up as long as the layer casting the shadow does not change position and the Light does not change position. The only thing that could foul that up is if the Shadow Catcher layer is not properly attached to the shadow casting layer. If the geometry is off there, the shadow will move when the camera moves because the layer catching the shadow does not share the same plane as the layer casting the shadow. 

To be sure I would need to see a screenshot with the position properties of the Shadow Casting and the Shadow Catching layer revealed. The rotation properties should share the same intersecting coordinates. To make this easier to diagnose, I always align the anchor point with the bottom center of the shadow-casting layer and make sure that the rotation and orientation properties match up on both layers. 

If you can, copy and paste a screenshot showing all of the transform properties of both layers to the Reply field instead of using the Drag and Drop here button so we can see it in your post. The toolbar also has a button to add photos.