I have a problem with the G27, as if it detects it, but I can not change any button / axis and I can not drive with the steering wheel. The mouse cursor on the menu is also locked and I can not select any option (none of the G27 buttons does not respond). In every other game the steering wheel works properly.
Try reinstalling drivers? My G27 works perfectly. All buttons bound through game. A friend who has the G27 also has it working perfectly with nothing needing to be done to make it so. We even both have it unlocked to use full 900° rotation. If there's a problem, it's almost certainly on your end.
That said, you can also use Logitech Profiler to see if that fixes your problems.
Same issue with my G29 and even worse with an additional gamepad attached. (in that case i get stuck in the main menu and have to exit with task manager). No problem at my side with the wheel and all my other games (AMS, AC, rF2, PC, GTR2, R3E, LFS, ETS2, ATS, CityCarDriver and some arcade racers more).
The reason for me to refund the game and if it won't be fixed soon, i'll forget MR, like i forgot ST.