i sent you down a dead end path, i think. i can’t think of how to separate out track 7 for midi bass.
if it was track 3, for instance, you could use string mute and send only audio from 3 back out to protools for use with midibass. or even load midibass as a vst within mg3hex.
i’ll experiment and see if i can get it to work.
i have not experienced the lag you describe. does it also occur when mg3 standard is loaded on a protools track without metaplugin?
are you mixing your bass sound in with the synths? uvi/arturia presets would probably be more responsive (lower latency) when triggered by guitar.
once you get this solved take a look at @prehm ‘s bass trick, it is the lowest latency option and is a lot of fun to play: