When I hooked mine up first, I forgot to plug in the power supply. It did exactly that, all except steering worked.
Maybe check the power supply is fully plugged into the wheel, the wall adapter is fully in the box and I think there is a light on the box too.
I have a G25 and I use electrical tape to keep the wires in line, also use "Tool Drawer Liner" under base, keeps down a lot of noise with wheel.Had the very same thing happen to me today.
Quite annoying since having to unclamp and unscrew the G27 from my playseat evo is not a task one wants to do very often.