I may be experiencing something similar.
Starting Wednesday, 17 July, (last successful sync Tues 10pm), my FitBit kept reporting sync failure, even though some of the stats, like Steps, Active Hours showed in my app, others like Exercise, did not. On Thursday, 18 July, the same happened only now it showed no data from Wednesday. Today, 19 July, I tried more aggressive action - restarting phone and Ionic, removing device (it failed to reconnect, although the first pairing step where you put in the 4-digit code succeeded), then finally a factory reset on the Ionic. During the setup of the Ionic, the Ionic died during the software update, and will not turn on again. I've tried the Leftbutton/Bottombutton long hold, but no response from the device. The device was fully charged when I did the factory reset and remains connected to power. Seems like the device has gone permanently dark.
