CC 12 Issue

I have a problem with a consistent feed of cc12 messages to Nuendo. Every time I record midi data, notes and modulation it also unwittingly records CC12 message data. I don’t have any controller setup to output this data, nor am I touching any knob or fader to do so? Any suggestions where this mysterious output of data to Nuendo could come from?

Sounds much like an unused input device (wheel? knob? fader?..) that creates data erratically. As a quick work-around you can always filter it out while recording.