With the DVS Expansion Pack enabled, you are unable to record analog sources in the mix, such as line, phono, or microphone inputs. However, if you disable the DVS Expansion Pack, then you will be able to record within Serato DJ from these sources.

This is a limitation of the hardware and cannot be resolved.

As a workaround, we recommend to disable the DVS Expansion Pack if you will be using and recording external audio sources.