Is this working the way it's supposed to?
Normally, when a track's 'Master/parent send' (M/PS) is disabled, the track's I/O button shows red text to indicate that the M/PS is turned off. In the pic below, even when the M/PS is turned OFF, the presence of another 'regular' send keeps the I/O button in its ON state.
As far as the actual routing goes, when the M/PS is turned OFF, the track is, as expected, NOT sent to the master. But shouldn't the I/O button show that OFF status independent of the presence of other track sends?