I found this info in the attached FAQ document. Perhaps it might help you.
What happens in FMV if the camera is aimed at or above the horizon? If the camera is aimed above the horizon the metadata will contain values that can’t be resolved in the context of placing a videofootprint on the ground. As a result, you’ll often see oddly shaped polygons or no frame data at all on the map. In this mode, it is recommended to disable the display of the Frame Center and Frame Outline, and use only the Field of View and Platform displayed on screen to provide context.