Problem solved. I played around with the options some more and I figured it out. If you have Game Avionics Mode enabled in the GAMEPLAY section, then your Throttle (Page Up / Page Down) functions will not work even though they may be mapped that way in the controls section under GAME. Disabling Game Avionics will allow you to control your throttle properly. When using Game Avionics mode, all other controls seemed to work just fine in the startup procedure.