The new sync method is a step forward, but currently has at least 3 apparent bugs:
The worst is that not all segments that are starred and are on the route (Strava itself shows them as being on the route in their own route description) are included -- note that this has nothing todo with downhill segments, my starred segments are all climbs.
Interestingly this is also visible in the overview map shown in the Garmin Connect App. Here segments are marked with little violet flags, but many are just missing. Further, not all segments shown on the Edge are triggered. It is not clear which segments are included and why some are missing.
Another bug is the elevation, which is pretty random and especially on flat parts totally wrong, eg. showing 6k height meters for a course with only 500hm and even climb pro triggering on flat parts.
The third bug I could find are missing segments names, but this was already mentioned in the forum.
Is somebody working on these issues? Most issues are likely on the Strava side, but it would be good to know they know .. better would be that they try to fix this.
On the other hand why release a new feature when bugs are apparently present? Among the top 2 things I would unit test for here would be segments .. whatever ..