If the usual troubleshooting tips don't work (resetting interface, etc). Remove the midi driver by following the steps below

*** Make sure the MOTU MIDI Interface is off for this. ***

To remove drivers with terminal:

1. Make sure you're logged in as the administrator.
2. Go into the Hard Drive > Applications > Utilities and open Terminal.
3. Type in: sudo rm -R /System/Library/Extensions/Motu\ MIDI\ Driver.kext
4. Then press return. you will now be prompted for your password. Enter
it then hit return and it will complete the action.

Restart, then reinstall the drivers. It is always best to download the latest drivers from motu.com
NOT FOR PUBLIC DISPLAY ON WEB, but can be shared with individuals as needed.