Only the first four controller devices are available to be selected

I'm having a similar problem but it only recognizes 3 devices.

Primary Flight controllers are:

Thrusmaster T1600 stick

Thrustmaster T1600 throttle 

Thrustmaster Rudder Pedals

Saitek throttle Quadrant

Virpil Rudder Pedals

No matter what I do, I cannot get the game to recognize either of my rudder pedals when plugged in via USB.

If I have the Thrustmaster pedals plugged in to the throttle, they register perfectly fine as another axis on that controller.