Since updating to GE 6.10 I can no longer launch the app. It quits with the error message 'Cannot connect to the Garmin Express Service.'
Running Mac OS 10.14.1 on a 2015 MacBook Pro 15"
$ /Applications/Garmin\ Express.app/Contents/Library/LoginItems/Garmin\ Express\ Service.app/Contents/MacOS/Garmin\ Express\ Service
2018-12-12 14:38:34.102 Garmin Express Service[6919:540851] Garmin Express Service 6.10.0.0 has started.
2018-12-12 14:38:34:103 Garmin Express Service[6919:307] Garmin Express Service 6.10.0.0 has started.
2018-12-12 14:38:34:109 Garmin Express Service[6919:3a0b] Loading devices
2018-12-12 14:38:34:143 Garmin Express Service[6919:3a0b] Network devices not detected
2018-12-12 14:38:34:168 Garmin Express Service[6919:3a0b] Network devices not detected
2018-12-12 14:38:34:170 Garmin Express Service[6919:3a0b] Calling whereami for country code US
Illegal instruction: 4