Nav light problem with Cessna 172 and maybe more aircraft

I am using FSX with SP1 and SP2, no accel pack, no add-ons.

When I turn on the Nav Lights, only the wing tip lights come on. The tail light does not come on. When I turn on the Landing light, the Landing light comes on but the Tail light also comes on.

This happens when using the mouse on the switch panel or when using FSUIPC for FSX using external switches.

I don't remember this happening prior to SP1 but maybe I just did not notice it then.

Is this a bug in FSX?