Googling the issue led to this post from Avid:
https://avid.secure.force.com/pkb/ar...tor&popup=true
They advise creating another user account and migrating to it but that isn't practical for me.
Reading through this thread:
https://duc.avid.com/showthread.php?t=351337&page=2
Stuart Peck wrote:
Re: Editor - Error Initializing MIDI Engine
Hi,
I know this is an old thread but wanted to elaborate as I feel the Avid line isn't exactly the correct way to resolve this issue per se.
It is true that creating a new user will solve this but it is also true that this is a 'sledgehammer to crack a nut' approach. We don't have time to migrate all these settings and preferences when the user account isn't the cause of the fault.
The issue is due to the Avid midi setting that is created by default when you first turn on the Avid 11 rack. Quit pro tools, turn off the 11 rack and remove the 11 rack setting that is currently greyed out in your audio/midi settings. Turn on the 11 rack and you will see that it creates a new setting in your configuration window. In some cases, this will solve the 'Error Initializing MIDI Engine' when using the Eleven rack editor, a better approach is to create a new Midi configuration .
Go to /Applications/Utilities/Audio MIDI Setup and under 'window' click 'show midi window'
This will bring up your midi set up, on the left you have a configuration drop down which will probably be set to Default. Drop this menu down and create new, name the configuration. You will have to set up your devices again but when you start or plug in your USB devices it will create new settings.
This will solve the 'Error Initializing MIDI Engine' error when starting up Eleven rack Editor.
Hope this helps
Thanks, Stuart
__________________
Stuart Peck - Music Composer
I'm going to try what he suggests and see if it resolves the issue.