Make the camera visible. Load a box prop, move the prop next to the camera, use a six inch nail to nail the camera to the box! :lol:

Seriously though, that's one of the strangest things I have heard. I don' have a solution, but there is a workaround you could try. You should be able to make the Main or Aux camera fill much the same role as the top camera. Set the focal length to zero to kill the perspective. Set xOrbit to -90.0, set the other orbits to zero. Set DollyY and DollyX to zero, this puts the camera above the 0 0 0 point. Set ZollyZ 10.0 (or more, if you have a very tall item in your scene).

Use the Flat Hand camera control icon to move the camera in x or z. As for the dials, DollyX works as expected, DollyY will move in the world z direction, use scale to zoom.

Oh ye, then set the key to red, slaughter a chicken at full moon, and sprinkle its blood over your base unit, chanting  "resop, resop, resop", and prey that the same thing does not happen to your new "top camera".