Reply to MidiFighter 3D button as crossfader issues

Hi all,

Trying to map one button of the midifighter 3d to act as a crossfader set button. When I hold it down, I'm able to manipulate the fader fine under Fader/Knob as the type of controller, in Direct interaction mode. However, when I let go of the button the fader defaults back to the left deck. How do I get it to stick when I let go of the button?

Thanks for any help!