If the time is wrong, it will definitely affect your sync. If it is dropping time, it may be a weak battery. I think you can verify your battery status in Mobile Connect
Yes. It should be 12 months but it's hard to tell how long it was sitting on a store shelf. Use of a HRM and logging of activities will reduce battery life as well. Did you check it on Mobile Connect?
My vivofit won't sync either. It is now just stuck in sync mode and nothing I do changes it. Is there a way of turning it off and on again? Would that help. I've only been using it for a week or so and am ready to throw it away.
Here's a way to reset it if you can get to sleep mode.
Press the button until you see "SLEEP", then press it 3-5 times quickly until you see the FW version number, and then hold the button for 10-20 seconds. It's a bit tricky, so you may have to do it a couple times.