I think I am having the same problem.
I am recording interviews via an iPhone to podcast. The iPhone is connected via stereo cable to ST1. ST1 is assigned to channels 15 and 16 in the Setup/IO patch page. This works for recording to a Mac via USB but doesn’t show up on the Qu-Drive/multitrack page. I.e. There is no meter activity on these channels.
Very frustrating. Have I done this right? I am on firmware 1.9 rev 4537 if that matters.
I guess I could get a stereo to mono cable and go via one of the mono channel inputs.
Any advice appreciated.