Well, I had my FFB disappear two times now. While it is possible to re-plug the wheel mid-game (make sure to enter controller options afterwards so it is properly re-initialized, though - didn't know that one bit the first time it happened ), it happening every single time sure isn't exactly acceptable.
Maybe try setting up a new profile and see if it happens with that, as well?
Yesterday I connected to a server after racing on another server and FFB was not working properly. Then I went in Control options and hit the Reload button and luckily everything was back to normal again.