Fitbit Flex 2 is not syncing

[ANNEBP]

My flex 2 won't sync. I've had it on charge all night and the app is saying the battery is low (no emails to say battery is low) and whilst it was charging I did the 3 second reset. Nothing. 

I've reinstalled the app this morning and it's the same. I don't want to delete the device as it says all my old data will be lost and I've been using it to lose weight (successfully). What else can I do. I'm ready to throw it away. Very disappointed. 

Moderator Edit: Updated Subject For Clarity.

[RobertoME]

Hello there @ANNEBP, I was reading you have lost weight successfully and now your tracker is not syncing. Before move on, congratulations on your effort and commitment to have a healthy life! 

If your tracker is not syncing a good way to troubleshooting this issue is doing the step you have tried already. Rest assure if you set up your tracker again on your account you won't lose your historical data.

However, at the moment I would like to recommend to review the version of your app. Since you mentioned that you tried to uninstall and reinstall the app, probably you have the latest update. Just to cover all the possible solutions, it would not hurt to review this. There has been new releases that might improve the stability of the app. For more details review this post.

Regardless if it was require to update your app, I suggest to try the following: Log out from your Fitbit app and go to your phone settings. Access to the App manager option and look for the Fitbit app in your downloaded apps list. Once you are there, clear the app cache and data and proceed to "Force Stop" the app. Finish the workaround by restarting your phone. When your phone has initialized, go back to your app and try again.

Hope this helps and keep me posted how it goes.