Facebooks API was suffering from a bug that is creating discrepancies in post level data. This affected Supermetrics and any other service that fetches post level data from Facebook. Facebook addressed this by adding a new endpoint in the API for published_posts, which should return all published posted, not just those visible on the page feed surface (UI). (Original Bug Report and fix.)
Our development team has deployed the fix to our Facebook Insights connector for Google Sheets on January 19th, 2018. For Sheets users to access this fix, they need to add the following string to Options->Advanced Settings field in the sidebar:
You still must authorize your account at the higher permissions levels by logging out and in again after enabling this.
For Data Studio users, this issue has not yet been fixed and the connector is still using the original endpoint that has incomplete post-level data. We're working to allow users the option to enable the new endpoint in a similar way as Sheets.
**IMPORTANT** The new endpoint requires stronger permissions to allow for "managing your pages" so that it can function. It will fall back to the original endpoint in the case of certain errors. If you get the following error or find that post data is still missing from your report, please log out of the Facebook Insights connector and back in to accept the new permissions level.
Fetching Facebook posts requires new permissions ("manage Pages"). Please log out from the Facebook Insights data source and then log in again, granting the new permissions.