Denon dn-x1500 cuing issue need help

I've bought a Denon dn-x1500 off some guy and I've been using it for 2 months now, it is in great condition, he is trustworthy and everything worked perfectly until a few days ago. The way I'm using my headphones while DJing for example when I'm bringing a track from channel 2 in while channel 3 is playing. Channel 2 cued, fader all the way down so you cant hear it over master, while channel 3 is playing out master, fader all the way up, and cued on master. I can turn the cue pan knob to cue and only hear the track on channel 2 on my headphones while I;m setting where I want my track to start, and when I'd turn the knob to master I could only hear the master, and on the middle I could hear both at the same time. Now the issue that I'm having is that all of a sudden (I don't remember doing anything weird) I can not turn my master cue on, without split cue button being on. The only way that master cue turns on, is if I press the split cue button (does not work the other way around). This is very annoying, as I have to set it up differently and best I can do is hear channel 2 track on left ear of headphones, and the other one on my right ear once its split down the middle, I don't like this, I'm used the other way and sometimes I've got the headphones only on 1 ear. Any idea how to fix it? :001_unsure:

http://prntscr.com/il211o