Pioneer ddjflx4

What exactly do you mean by "sync controller to computer"?

Is there an issue connecting the controller to rekordbox?

Probably having the same issue i'm having, just bought the DLX4, have Rekord box installed. Plugged in the controller and nothing is happening. The controller has turned on, but Rekord box isn't seeing it from what I can tell. Was expecting a registration page to pop up giving me Hardware unlock.

Can you please file an inquiry ticket here and our support team will gather some additional information to assist you in resolving this issue.