I have had several instances with the new Garmin Connect where the watch appears to synch (I can see the moving bar on the faced of the watch), but then when I go to look at connect.garmin.com, there is no evidence that an activity has ever taken place. The main page, the activities page, and the the synch navigation item on GC either do not show the activity or simply indicate that there is nothing to synch.
Between the new express site being erratic, blocking my auto uploads to strava, and blocking my tanita scale from uploading (different USB ANT drivers?), I'm extremely upset with what I perceive to be a huge issue with your new Garmin Express software.
Please let me know what other information I can provide to get proper support.