Apple Health doesn't sync properly with Garmin Connect
I have Garmin Connect set up to feed steps to Apple Health but Apple Health consistently under tracks. So for example yesterday I did 11,200 steps on my Garmin Fenix 5 but Apple Health only shows around 1,700 steps. When I look at data sources in AH I can see entries from Apple Device itself and some from GC. So clearly there is a feed/connection established and open between Apple and Garmin, but for some reason Apple doesn't receive/count all the step data. When I raised this with Garmin support they said it's an Apple issue and there's nothing they can do. If that's the case then I would assume many if not all Garmin users are having the same problem? Any thoughts very much appreciated.
Garmin Fenix 5
iPhone 8 Plus, iOS 12 (problem was same on iOS 11)
Garmin Connect iPhone App up to date
Thanks!