Help!

“but consistantly on channel 16” that’s great.
Please do a following:

Test1:
Leave the console physical connection as you using today. Go to the settings/routing/Card out and swap the CH1-8 with the CH9-16 so Card out 1-8 should be CH9-16 and card out 9-16 should be CH1-8
Please tell me which channel(s) has issues in the recording

Test2
Connect the cable from CH16 then connect to the CH17. In the mixing console settings copy every single parameters from CH16 to CH17. Make sure the gain set to the same level like on CH16.
Please tell me does the CH17 has distortion?