Hey, ​@scott!

Try redefining Manychat's permissions by removing it in Facebook. Here's how to do it.

And if that doesn't work, I'd suggest opening a ticket to the Support Team: How to get support from Manychat – Manychat Help

Hope this helps!

Thanks a lot Fabio. 
 

Did it work, ​@scott? 👀

Yes, I have reached to support team and they give me some suggestions and steps, I am currenlty working on it.