I have a Saitek X-65F HOTAS system, which includes a joystick, a throttle and a button panel. I have programmed and used it with FSUIPC in both FSX and P3d without issue until now. The system has a possible 50 programmable buttons and when I tried to program buttons in the range 33-36 and 40-41 (all located on the throttle), I can't assign a task to them in FSUIPC. The other buttons on the throttle work fine with FSUIPC as do all the buttons on the panel and joystick.
All the buttons show up when pressed in the control panel app. They also show up fine in LINDA, which I don't use but I wanted to see if the buttons showed up. The X-65F is not assigned as a controller in P3d 2.1.