I have my joystick axes and buttons mapped through FSUIPC in order to bypass Windows 8.1 power management. On a flight from Auckland/NZAA to Melbourne/YMML, my joystick responded normally from aircraft spawn all the way up to FL360. At some point during my cruise, I noticed that my hat switch stopped working. I then tested other buttons and they refused to respond as well. I then went into FSUIPC and found that it did not respond to any button or axis inputs. I checked FSX control settings and found that the joystick did not appear as an option. What is interesting is that Windows 8.1 seems to recognize and respond to the joystick normally, and the VATSIM client vPilot responds to the joystick button which I have mapped to PTT. Plugging the joystick into a different USB port did not resolve the problem.
Why would I observe these symptoms, and what can I do on the fly to resolve the issue?