It would be helpful if you provided the versions / release dates of HW/SW. Here are some questions I have:
1) You mention that you “contacted Virtual DJ” are you able to replicate the problem with:
1.1) Serato DJ
1.1.1) latest version, 1.7.8;
1.1.2) last known stable version, 1.7.3
1.2) Serato DJ Intro (assuming that the3 N4 came bundled with this)
1.3) Virtual DJ: (any versions you have used)
If anything here works, it might be a SW issue;
2) If you have the same or similar problems — or even if you don’t — I have found numerous problems within my own MacBook Pro Retina mid-2012 model that Apple support teams on the phone and in the store have tried to unload on my controller — a Denon MC2000. Because Denon was acquired by Numark, it seems like a safe place for Apple to dump all problems, believing that no one from Numark is going to bother supporting Denon equipment, but Numark seems to have taken control of the Denon range and have flipped my problems back to Apple. Despite the contract I have for Apple to provide support, I cannot get them to look at the problems I have even when I am not having the same issues on my PC running Windows 7. I have found going to an Apple Store in person is a much more fulfilling experience than their telephone support, but it is frustrating the way that Apple works. Rather than focusing on what they can do to make your Apple experience better, many of them are so focused on how much they can handoff to other non-Apple-related vendors. So far, Numark has been able to identify 3 problems withe Mid-2012 Retina and Apple has identified nothing and only able to fix one of those problems, albeit, reluctantly. My point here is that I wasted a lot of time by walking away from Apple and if I can help anyone else avoid that pain, I am pleased that my journey had was useful.
Not the response you wanted, I know, but I hope you are able to salvage something from it.
Good Luck!
