I've been having sync problems since the updates, too. And it's unpredictable. Apparently if I'm at work, sync will work (most of the time), but at home, hardly any of the time. It took me three hours to get it to sync last night. Fitbit try to tell me that it must be my phone, but I had no problems of that nature until the forced upgrade of the app. I acknowledge that this is how business is done these days, but I object to forced upgrades. I think it's offensive and an invasion of my privacy and right to choose.
Ultimately, the biggest issue I've had with the app is in how unstable it is. It crashes at the slightest provocation, more pronounced when using Fitbit Communities, reading posts, and participating in discussions, but really, at any time.
So they release a face lift that does nothing for the stability, and makes the app's handling of bluetooth worse than ever. And I no longer have stairs measured. The home dashboard screen takes ages to update. I've synced, checked the step count, and seen that it is accurate, but on returning to the dashboard, the step count on the dashboard still displays the step count prior to syncing. Last time, it stayed that way for something like 20 minutes.
They're so focused on delivering new features and a new "customer experience" that they've forgotten to iron out the bugs. Goodness knows what their test teams are doing!
