I ran into a weird bug on OT MKI 1.40A. Could not play a C2 (or C3? that whole midi instruments being off by an octave thing…) on a midi track set to midi channel 5 via midi or pressing trig+yes for a trig with that note. I could play the B just below and the C# just above and tried a whole bunch of other notes. I tried using midi channel 4 and 6 and they worked fine. I tried using different midi tracks, I tried swapping out the controller and synth being controlled. I created a new project, checked and rechecked my project settings. It was only channel 5 and that one note as far as I could figure out.
I upgraded to 1.40B and the problem went away.