On my Fenix5x not all starred Strava segments are synced (from totally 40, app 20). I do the sync over Garmin Connect on phone and also over Garmin Express on Mac.
The second question is why are not transferred my personal records to the watch (of course, on those segments that are synced to watch). Of 20 synced segments, only 2 have my PR transferred (KOMs and Rivals are transfered on all Public segments). Some of synced segments are public, some are private.
am I missing something? I have Strava premium account.
