When I setup my multi track audio interface to audacity via USB and then select it as input, change the number of tracks to be 8 mono and hit record, the first 2 tracks come in as a stereo track. The left being track 1 and the right being track 2. I usually pause the recording and split to mono, but I would really like to fix this issue. I’m using the latest audacity 2.3.2, I have a 2nd computer that doesn’t do this and it is on audacity 2.2.2 but I can’t get the older version of Audacity to work on my device so I’m stuck with the latest release.
I’ve not heard any reason for intentionally making this change in Audacity, so I’m inclined to think this is a bug and shall log it on the Audacity bug tracker.
As a workaround, if you enable the “Full” set of keyboard shortcuts (see: https://manual.audacityteam.org/man/keyboard_preferences.html), then before you start the recording, you can hold down “Shift + Ctrl”, and type nnnnnnnn. (“Ctrl+Shift+N” is the shortcut for adding a new track), then “Ctrl+A” (select All), then “R” (record).