thanks for the helpful suggestions.

i’ve yet to find a method of reliably reproducing the
symptom (the steady red light for SRC3) of whatever
the underlying root cause of this happens to be…

it only happens (when it does happen) when
at least two SRC3 inputs are set (to anything).

Baddcr: the red light will only go off if I turn all
SRC3s for all tracks to “-” and yes, it will come back on steady red
with no input monitoring
again if any of the tracks’ SRC3s (tracks, main,
or cue) are activated, even if there is no sound going
at all, OT’s sequencer stopped.

Once this “stuck” light comes on, the only way to get it
off, besides turning all SRC3s to “-” is to reboot.