Garmin Vivofit 2 and autosync issue.

After digging a lot and spent much time on the Internet I found this explanation on Garmin site regarding the autosync issues. So, the conditions that must be meet are the followings:

The vivofit 2 will autosync to your compatible smartphone once you reach 2000 steps within 60 minutes¹ or after an activity is recorded.
In addition the following requirements must be met as well.

• The device must be in its normal page loop, not on the sleep page.
• The device will not sync when using HRM or in an activity.
• The device will only sync to connections that have successfully paired in the past.

The vivofit 2 will time out after 8 seconds when trying to autosync, or 30 seconds for the manual sync. By default the device will attempt only 8 auto-syncs per day, regardless of success or failure.
¹This count resets after every successful sync, manual or auto.

Original Garmin post here.