After updating my iPhone to the latest version of iOS, my Fitbit would not sync with the app. I logged water and it didn't save. Unpairing the device didn't work. Deleting the app and reinstalling on my iPhone DEFINITELY did not work. When I tried to log in, the app was left in "login limbo" meaning, it wouldn't tell me if my password was wrong nor would it log me in. When I tried to reset my password, I got the message seen in the attached screenshot.
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Hello @LurleenLumpkin, thanks for joining us, it's great to see new faces around! 
Have you tried to log in through the Fitbit website? If you're still not able to log in, please try to restart your password through the site. If you are able to log in, please go to the Settings on your phone then to General > Date & Time and make sure Set Automatically is enabled, then open the Fitbit app and try to log in again.
Now, in regards of your water logs, once you're able to access the Fitbit app, input a water log and check if it's now showing. If not, please let me know.
I hope this can be helpful, if you need anything else, please feel free to reply! 
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