Using XBOX 360 controller vs SHIELD controller?

I’m really enjoying RetroArch on the SHIELD TV, but I’m having trouble with the capacitive buttons on my SHIELD controller. As a result, I’ve been primarily using a wired XBOX 360 controller. All the buttons map fine in RetroArch, but I can’t control the menu. Is there a setting I could adjust which would allow RA to recognize the 360 controller as the primary input device? I’ve tried starting the system with only the 360 controller connected, but still no luck.