FLX6 Jog Wheel unresponsive when connected via Phono to Phono

Hi all.

I bought the DDJ FLX6 last January from a retailer in Belfast and have played a number of clubs, weddings, events and bars since. The controller has served me really well and would recommend for mid-level. 

I noticed at a previous venue a problem before where one of the jog wheel tops when trying to queue tracks was unresponsive. After the gig and lots of playing around with the controller and without issue, I thought nothing more about it and put it down to a glitch. 

Last night I was playing a venue and noticed the right jog top was unresponsive when I was about to start. Not ideal. After a bit of unplugging and restarting I noticed that when I removed the phono to phono cable to the club's DJM in-house mixer, the wheel was suddenly responsive again. When I put the cable back in, it was unresponsive once again and was the same for the rest of the gig. This meant I couldn't drop in tracks like I usually do. I realised this was a similar scenario to the previous example where I was connected via Phono to Phono on a different in-house mixer.

Is there a fix? A 12 month warranty replacement? Not sure where to turn.