Flex not syncing with iPhone

[GrphcDsgnr22]

My Fitbit flex was fine on Sunday however on Monday it synced on the morning and has not synced with the iPhone app since. It doesn’t seem to be able to find it. I’ve turned Bluetooth on and off, forced quitting the app and restarted the phone. I’ve tried restarting the flex this morning and it synced once, not syncing now. I charged it last night and it was full but this morning it’s gone down to one bar. Any help? I’ve never had any problems with the flex before. Thanks 

[MarcoGFitbit]

Hello @GrphcDsgnr22, thanks for joining the Fitbit Community, it's great to have you on board! 

I appreciate you have brought this to my attention and for letting me know the troubleshooting steps you've tried so far. At this moment I would like to suggest you to try the following:

• Make sure the latest version of the Fitbit app is installed on your phone.
• The software on your mobile device is up to date. To check, tap Settings > General > Software Update.
• Make sure there are no other Bluetooth devices around as they might interfere with the syncing process
• Check that your Fitbit device's battery isn't critically low.

If your device still won't sync, try these steps:

1. Force quit the Fitbit app. 
2. Go to Settings > Bluetooth and turn Bluetooth off and back on.
3. Open the Fitbit app.
4. If your Fitbit device didn't sync, restart your phone again.
5. Open the Fitbit app.
6. If your Fitbit device didn't sync, restart it one more time.
7. If your Fitbit device won't sync after the restart, log in to your Fitbit account on a different phone, tablet, or computer and try to sync.
8. If your Fitbit device still doesn’t sync, remove all other Fitbit devices from your account and from the list of connected Bluetooth devices on your mobile device and try to sync.

I hope this can be helpful, give it a try and keep me posted in case you need anything else.