DJM 900 Nexus Cue Issue

I've looked around and I haven't found a similar post with this issue yet...

I've owned the DJM 900 nexus since it came out and just a few weeks ago all four of the cue buttons above the faders just stopped working on me. The backlights of the buttons still work but whenever you click them they don't light up and don't send to the headphone out. Both the cue button below the master and one above the fader start both still light up when clicked and work. I've tried just about everything from resetting the mixer to the factory settings to reinstalling the firmware and none of this has seemed to fix it... Some help to remedy my situation would be greatly appreciated. :-)