Can you confirm that you can't see the sync button in the app build from the clean template?
The sync button is present and working in a blank app generated using the mmw-advantage template.
It's probably caused by your modifications.
I will need access to your modified app. Can you send it to me?
How do you want me to send it to you? Direct message?
I built the Android project and there is the synchronization button (top - right corner) , but the buttons don't fit. Maybe on your device it's covered by another button.