I was driving something the other night and happened to run into the same problem Soks! I forget which car it was (possibly the AARP Cuda) but the problem was caused by the Fully Custom Racing Transmission upgrade, with the custom tranny the H shifter on my G27 did nothing but the flappy paddles worked just fine.. I put the stock transmission back in the shifter worked fine, so I'm thinking there's something funky going on with certain cars and the custom trans (I assume it's only certain cars though as I'm sure we'd have heard if it affected all cars with fully custom transmissions).