Fitbit won’t sync, removed from account and now I'm unable to add it back.

[Jibanyah911]

My Fitbit stop sync to my phone since IOS 11.1 updated last weekend. I follow the suggestion to tried many way, it still not sync, then someone suggested forget this device and re- connect, and every time it founds my tracker but just never can re-connect my tracker with my phone. Now Fitbit works on its own but doesn’t connect to anything, the problem seems between Fitbit and phone, I am thinking that Fitbit app maybe updated but I never see.

Moderator Edit: Clarified Subject.

[MarcoGFitbit]

Hello @Jibanyah911, I hope you're doing well, it's nice to see you around. 

I appreciate you have tried some steps to try to resolve your issue. Have you updated the Fitbit app recently? If so, I would like to suggest you the following steps (as I'm not quite sure about the steps you've followed):

1. Restart your tracker, then leave it plugged in and charging. 
2. Restart your phone. 
3. Update the app and the OS on your phone if you haven't done it yet. 
4. Make sure you have a strong WiFi signal.
5. Make sure there are no other Bluetooth devices that might interfere with the setup process. 

Then, try to set up your tracker as a new device:

1. Go to the Bluetooth settings on your phone and check if your tracker is on the list of paired devices. If it is, tap on it and select Forget this Device.
2. Open the Fitbit app and tap on the Account symbol at the top right corner of the screen, then tap on "Set up a New Device"
3. Choose your tracker and follow the onscreen instructions to continue
4. When (or if) the app asks you to replace your current tracker, please replace it and continue with the process.

I hope this can be helpful, give a couple of tries and let me know the outcome.