To sync any activity data from your Garmin device via the Garmin Connect app, you must first ensure that the Garmin Connect app is connected to Apple Health, and that the activity sharing settings are set to 'everyone'. 

To connect Garmin Connect to Apple Health:

1. Launch Apple Health

2. Tap your profile photo

3. Under Privacy tap Apps

4. Tap Connect

5. Tap all the toggles on to ensure you've granted Apple Health access to your Garmin Connect data.

To connect Apple Health to Garmin Connect:

1. Launch Garmin Connect

2. Tap  More ••• > Settings > Connected Apps

3. Ensure 'Apple Health' is listed under 'Connected Apps'.

To change your global privacy settings in the Garmin Connect app:

1. Tap  More ••• > Settings > Profile & Privacy

2. Tap Activities 

3. Ensure 'Everyone' is selected

To change your privacy settings for a specific activity in the the Garmin Connect app:

1. Tap the activity you would like to sync >  ••• > Edit Activity > Privacy 

2. Ensure 'Everyone' is selected