Only playing midi when drum map is off
Right. So drum maps are kind of a hold over from the old days when we all used hardware samplers, and outboard gear.
Lets say you have 2 external synths/samplers/romplers. Each has a different internal arrangement of midi notes to drum sounds.
A drum map “maps” incoming midi notes to different outgoing midi notes. The idea was that you’d have your midi drum track playing an external synth and if you wanted to change to a different external synth, you’d use the “drum map” for that different external unit and the correct drum sounds would play. It worked, more or less.
So with a drum map on your GA track, the midi in notes are being mapped to perhaps notes that your vst instrument has no sounds mapped to.