Hi Choyin ,
Welcome to the community!
Is your Facebook Page perhaps in private?
The chat box will not appear if the Facebook Page is set to private.
Could you also check if your site has the script:
<script async defer src="https://connect.facebook.net/en_US/sdk.js"></script>
A plugin or theme might be including Facebook's old SDK. It conflicts with the new SDK and doesn't let the chat box appear.
A couple of reasons why it might not be working:
- Using a localhost or IP address.
- Accidentally not clicking the save button after whitelisting the site.
Let me know if any of these reasons is causing the issue!