Official comment
@Danilo > Try changing the audio buffer:

Set it to at least 1024 samples and see if that resolves the issue you're having.
If the problem persists, check that you have the latest version of rekordbox (currently 4.3.1), and that you have all operating system updates installed, and if you are on a PC, check if there are any BIOS firmware updates available from the manufacturer, and that you have the current graphics drivers available from the chipset manufacturer, not the Windows update:
If you still have problems, try using a different USB port and/or USB cable.