I have a Fenix 5 Plus and am having some very frustrating issues with syncing to the Android Garmin Connect app.
When I run say 5km on the treadmill, the km intervals are announced through my headphones reasonably accurately. However, at the end of the run my device shows 8km.
It looks like Garmin Connect thinks I've run 5 miles and converts it to km.
I have my Fenix, and both Garmin Connect & Strava apps set to metric, but this problem continues.