MainStage can't differentiate between keyboards

Hi! I'm trying to set up 2 keyboards in MainStage, but if I press a note on one keyboard, it detects it as coming through both keyboard channels. I don't know how to fix this, there's no obvious setup (the "MIDI Setup" in the settings just takes me to Audio IO lmao). I want different sounds from each keyboard, but one keyboard triggers everything. Help pls