If you find that your social inbox is not pulling in your community engagement, it's most likely due to a missing permission needed from Facebook.
Step 1
Click 'Add Account' next to Facebook to go through the Facebook connection prompts again for the affected account.
Step 2
Click on 'Edit Settings' to verify that the settings are all enabled, specifically "Manage accounts, settings, and webhooks for a Page" is toggled on, and click 'save'.