The “Send MIDI Notes” example composition outputs to the first available MIDI device, which may or may not be the one you want. You should check what the first available device is on your system and make sure it’s configured to send to Garageband or Mainstage.
To send MIDI to another app, you need to:
- open macOS’s Audio MIDI Setup app
- open the MIDI Studio panel
- open the IAC Driver panel
- check the “Device is online” box
- click the plus to create a port
- select that port as Vuo’s output and as an input in Garageband and Mainstage
https://www.snoize.com/MIDIMonitor/ is handy for troubleshooting MIDI.
Does that solve your problem?
@balam, if you’re still having problems, let us know. I’m closing this since there haven’t been any activity for a while.