I recently bought an XBox Elite and the Elite controller that came with it worked at first when I bought the game but then suddenly stopped working for no reason I could detect. The controller works fine with all my other games and always has. A few weeks later, I accidentally discovered that pressing the right thumbstick resets the buttons but only temporarily. You have to keep pushing it periodically to keep the buttons working, and if you push it at the wrong time it can actually prevent the buttons from working. Needless to say, when the punches and kicks are flying this can prove to be a quick ticket to a loss.
Interestingly, I ordered a regular non-elite controller which arrived today. When I used it to play earlier it worked perfectly, just as intended. Given the evidence, I suspect some kind of software update bug in either the controller or the game itself, but I have no idea which.
Thanks for looking into this.