I have a new Fenix 6 Sapphire, and can successfully sync all my activities--Run, MTB, and Swim--to Garmin Connect.
My Run and Swim Activities sync with Strava. My MTB Activities do not. I have to upload them manually.
I have confirmed all my settings are correct, and have twice disconnected and reconnected the two apps, to refresh the connection. If I make a quick test run Activity, it updates very promptly. MTB does not.
Any ideas what's wrong?