It is probably working sometimes and not others because you are unplugging it and the controller ID is changing.
The solution is to leave it plugged in.
Logitech wheels work fine for NullDC or any other program that accepts input from an analog direct input controller (i.e. any game controller made before xbox360 controllers became the standard for pc games).
If you want to remap buttons or have the buttons post as keyboard keys instead, use Logitech profiler software.