garageband midi timeout catalina

I have not seen recent posts regarding this issue.

I don't recall making any recent changes.

Macbook Pro 2013 running Catalina.

Upon opening Garageband 10.3.4, I get the MIDI timeout error message after about 5-10 minutes of the spinning beachball. It says close, restart and if it persists to update drivers (would be a better message if it identified where the problem lies).

As with older posts, restarting does nothing to fix it.

However, after I click 'OK' on the error message, Garageband seems to run fine.

The issue does NOT happen with my Logic Pro X 10.5 software.

Can someone point me to a method for tracking down the culprit.

To the best of my knowledge, here is what I'm running:

Nektar Panorama P6 midi controller (I believe does not require drivers for Mac)

M-Audio Keystation88 midi controller

Korg NanoKontrol 2 midi controller

Focusrite Clarett 4i4 Pre

Plugins include Ravenscroft 275, TruePianos, Kontakt Organs, maybe one or two others - none of these are used much at all.

Any suggestions are appreciated, thanks!