That's normal. The 'hard lock' is only available in 200 degrees mode. It's the one you can hear clicking loudly when switching between 200 degrees and 200+ degrees. It's not a force feedback effect though, it's a hardware stop that has only 2 positions: 200 degrees lock, 900 degrees lock.
For any other setting, the steering wheel will use it's force feedback to simulate the turning ends. So yes, you can easily turn beyond these limits since the power of the force feedback is limited, but turning further doesn't affect your in-game turning circle. It would have been nice if they'd allowed hard locks in a lot more positions, but that would probably have made the wheel more expensive. Money they better use for a better set of pedals
Btw, you use the full 900° rotation mode. That's a bit pointless as it makes you have to steer a lot more than the cars do in reality. Streetcars (also the ones in LFS) have a full turning circle of 720°, racing cars (like the GTR class in LFS) 540° and open wheel racers even less (I believe 270°, but I'm not sure - I never drive these cars).