Most common causes for Facebook would be the account owner or someone with access changed the Facebook App Permissions, Removed the App from Facebook Business Integrations, or reset the Facebook password. 

If your curios about the disconnection, please reach out to the all Facebook users. Then user will proceed to reconnect the account. Select 'Facebook' and be sure to set each permission and confirm which pages are mortgage related. 

Here is the step by step for each:

Mobile App User, click HERE

Web Users, click HERE