I have MyFitnessPal, Strava and Withings as APPS/Sources in the Health app, however I can not see Connect as an option.
What am I doing wrong?
This might be a long shot.
Are there any registered device(s) in this app?
Can you create a manual activity or enter a weight?
Do you have a connect account? All data goes via the Garmin server.
It is possible that you need a device and data before it will request data to be send to Health app.
I found a work-around!
I'm having the same issue, but I hacked a solution!
If connect your Garmin Connect <> Strava and then give Strava write access to your Health data, Strava will write activities into your Health app from your recorded Garmin data!