When my watch connects to my phone over BT to sync activities only the very latest one is synced.
For instance if I have not synced for a couple of days and have 2 or more activities stored on the watch when I then connect to my phone only the latest one is synced.
When I look in the watch I can see all the activities in the history.
Phone Andrioid 4.4.2
Watch Software Version 2.80
Regards
Allan