I'm also having problems setting up my Xbox One controller. It works great for NES, SNES, Genesis emulators in Retroarch... But some of the buttons don't work right when using Mame. I'm using Mame 2016 in Retroarch... I've also tried Mame 2014 with the same results. For some reason left trigger is always TAB, right trigger is F11, L3 is F2, and R3 is F3. Yeah, I could map these buttons to something else, but then I'd lose the ability to hit the TAB button to bring up the Mame menu. Any ideas on how to fix this?