Hi,
If you have an issue with Sync and Notification follow this instruction that I just posted in forum.
I tested on my 3 android devices and works perfectly. None of my device are yet compatible with Fitbit
Settings > Apps > go again to Apps > find Fitbit > find Power usage details > App launch >
turn off "Manage automatically" and all other option, ONLY keep on "Run in Background"
Hope that helps
Best Answer