I'm glad to see that the problem is just not my Fitbit Flex. After updates on August 8, I could no longer sync mine either. I've done all the steps and still nothing. I even spent 90 minutes at a Verizon store trying to get someone to help me. They couldn't figure it out.
The next day I called Fitbit Support for help. Worthless! All the person could do was offer me 25% off my next purchase which is good for 30 days. If this is a well known problem then why can't it be fixed! Samsung would you not TEST your updates before automatically messing up other's phones. My Fitbit is work related to keep my monthly insurance cost down.