A part of my favourite Strava segments do not show up in my Garmin Edge 520. Here is a screen shot of a part of my favourite Strava Segments:
Here is a screen shot of the segment list that are in my Garmin:
As you can see, some segments are missing (road bike on gravel, chemin de l'aéroport) while some others are there... My favourite segments have not changed since a few months, so this is not a matter of Garmin not been synchronized...