Anslog Four + MS20 Mini + OB

I have my MS-20 mini running into the left external input of my Analog Four, recording through OB. Ableton Live 9.6.

My problem is I can only record a stereo clip from the MS-20 in OB.

I can drop the utility in Ableton on the track and monitor in mono, but anything I actually record is a stereo track. Does anyone know anyway around this? Sorry, I know the answer may well be ‘it’s obviously not possible’, or ‘it’s obviously done like this’, so excuse my ignorance!