you'll have to understand that all MIDI that goes into a bus or track's plugin chain also goes through to the designated output bus if the "monitor" switch is on (aka. "pass-thru")...
when Track/Auto-Monitor is on, it functions as if "monitor" is temporarily turned on for the current highlighted track, with the extra convenience to automatic MIDI-track/channel filtering--a convenience that maybe welcome for single live keyboard/controller players but probably nuisance to general orchestration workflows...)
this is all like so since the beginning, eons ago, so don't try to call it a bug ;)
you'll have to understand that all MIDI that goes into a bus or track's plugin chain also goes through to the designated output bus if the "monitor" switch is on (aka. "pass-thru")...
when Track/Auto-Monitor is on, it functions as if "monitor" is temporarily turned on for the current highlighted track, with the extra convenience to automatic MIDI-track/channel filtering--a convenience that maybe welcome for single live keyboard/controller players but probably nuisance to general orchestration workflows...)
this is all like so since the beginning, eons ago, so don't try to call it a bug ;)
seeya.