Fitbit Ace stopped syncing to child's iPhone

[Lou1975]

Hi my sons Ace has stopped syncing with his iPhone. I have read and followed advice on the forum but to no avail. 
E.g. I have tuned Bluetooth on and off, the phone on and off, reinstalled the app, restarted /reset the ace, ensured software up to date etc.

My son can log in and see old data etc on the app, but it just won’t sync any more, it always says ‘looking’ when I try to sync and it won’t appear on the Bluetooth on the phone - other devices can and it used to! 
Help?

Thanks!

Moderator edit: subject for clarity

[LiliyaFitbit]

Welcome back to the Fitbit Community, @Lou1975. 

I appreciate your participation in the Forums and sharing that your son's Fitbit Ace stopped syncing with his iPhone. I understand how you are feeling and appreciate your troubleshooting efforts and the additional details. I recommend doing the following to confirm that your son's Ace tracker is paired:

1. Log in to your Fitbit account.
2. On the Today tab , tap your profile picture.
3. Tap My Family. 
4. Under your child’s name, tap Switch to Kid View.
5. Tap your child's profile picture, and check if the Fitbit Ace is showing. If the tracker is not showing, please tap Set Up a Device and follow the on-screen instructions.

You can find more information about setting up and syncing Fitbit Ace in this help article: How do I set up Fitbit Ace devices?

Let me know how it goes, I'll be around.

[Lou1975]

Thank you for your response. I have followed those instructions and it is showing there. The device is still not syncing and keeps going blank despite being fully charged.

Sent from my iPhone

[LiliyaFitbit]

Hi @Lou1975, thank you for your reply. I am sorry for the delayed response.

I appreciate your efforts and the additional details. Since the issue persists, I've sent your information to the Customer Support team so they can get in touch with you and provide further assistance. You should be getting a reply soon. 

Let me know if you have any questions.