I don't think we ever figured this one out. If you can't do orientation or hover training at "Flight School", then something is definitely wrong with your setup.
Have these options always been grayed out for you, or did they become grayed out sometime after you installed?
If it were me, I would try deleting my .INI file. Perhaps some flight or airfield option you chose at some point had a side effect of disabling the training. Deleting the .INI file should set you back to the defaults, but that's a pure guess.
Also, I don't know if anything bad can happen if you delete the .INI. It seemed to work OK for me once. I had an issue once with G4 where if I ever changed airports, the game would error out when I quit. The result of which was when I restarted I'd be back at the same airport I tried to swap from. I was able to fix this by deleting the .INI file associated with G4. However, I don't recall where it was or what it was named.