Which phone do you have and is it on the list of compatible devices? click to see
You try anything here on the article for trouble syncing? see if any of this helps - click to read
Best AnswerNone of the suggestions in the article worked. The Fitbit app continues to say No Device Found and won’t sync.
I just started to get syncing problems with FitBit-Flex2 and Samsung A41. It refuses to sync until I restart my phone then it works for a few hours.
This has been happening for about 3 days. Before that it was extremely reliable.
My wife also reports the same issue and she has an IPhone
regards