v4.0.22.0 for Mac is available:
Garmin began rolling out Garmin Express v4.0.22.0 for the Mac today. If you would like to upgrade to the latest version, Check for Application Updates by clicking “About Garmin Express” from the Garmin Express menu bar, and then click “Check for Updates to Express”. This version includes the following changes:

• Fixed an issue that caused a crash on Garmin Express start up.
Spoiler: source
https://forums.garmin.com/showthread.php?251445-Garmin-Express-Release-Notes


Spoiler: download
http://download.garmin.com/omt/express/B/GarminExpressInstaller.dmg