If notes from your keyboard are sustaining that shouldn't be while using MainStage, you can narrow that down by asking yourself a few questions:
1. Are all of the notes sustaining out all of the time on all patches? This would probably be a sustain pedal polarity issue, and we would need to reverse the polarity. Here is a tutorial for this:
2. Do the notes sustain, but then stop sustaining sometimes when you press the sustain pedal (the sustain pedal will feel like an on/off switch rather than feeling inverted). If so, you might check that in the Layout mode, the sustain pedal type is set to “Press / Release”.
3. Are notes only sustaining during the time at which you switch a patch? This is a MIDI/MainStage issue where if you switch a patch while still holding the notes (and/or the sustain pedal), that instrument plugin in the previous patch never receives a note off MIDI command. We would recommend that you try not to hold onto notes while simultaneously switching patches.
4. Do some notes sustain randomly while playing a patch (not during a patch change)? If so, this is generally an auto-save issue (though I believe your autosave was turned off- but you can check that as shown in this video:
5. Is it only ever a certain channel strip that sustains? If so, you might try saving that channel strip, then deleting that channel strip, and then reimporting it.