Force RGB possible with AJA Kona LHe?

I'm trying to figure out how to utilize the "force RGB" setting in Color. My system is a Mac Pro with ATI X1900XT graphics and an AJA Kona LHe card connected to a Sony PVM-14L5 via analog component output. The Sony can switch between RGB and component on the same inputs, and the Kona control panel allows the analog HD output format to be switched between component and RGB. The trouble is, I can't for the life of me seem to make the force RGB feature work in Color (v1.0.1). I'm attempting to do this with a 720p project. The Kona and Sony PVM otherwise work perfectly with Color, as long as the force RGB button is not checked.

The Color manual states that playback performance may be improved by offloading the RGB>YCrCb conversion to the broadcast video card, but whenever I check the force RGB button all I get on the broadcast monitor is a green screen. I've tried different combinations of selecting RGB or component OUT on the Kona and RGB or component IN on the Sony, but no joy. Am I misunderstanding the proper use of the force RGB button, or is my hardware not capable of utilizing this feature?

Any guidance would be helpful, thanks in advance.