Hello, I post it here as it seems to me the most promising thread :) . Well, the fact is that GarageBand definitelly misses midi events, or at least ir seems to me. In the beginning I thought it was an electrical issue, because unplugging the computer and the keyboard from the mixing board worked. But still there was the stuck notes issue (plus de sustain pedal issue, which I have left aside). As reported by Midi Monitor ( https://www.snoize.com/MIDIMonitor/ ) , the note off events are arriving. But GarageBand ignores some of them. Furthermore, depending the sound choosen, Garageband ignores more or less of these events. I am looking for some kind of sampling over midi events parameter. But I don't discard that it is a GarageBand bug, as shown in this other post: https://apple.stackexchange.com/questions/113112/stuck-notes-with-a-midi-controller-and-garageband-10-0-1 Any advice is welcome. Thanks.