You may face an issue where the activity stream is not showing anything, and the software is displaying that there are no posts to show.
This issue is likely that the Users ID is not being synced between Social and SharePoint. The reason for the mismatch could be due to a Windows Server patch/update, SharePoint CU, or even SQL updates and it can be solved by using the UPA migrator. A set of scripts is used to correct errors for the cases where RecordID's in SharePoint's User Profile Service becomes mismatched with those in the Social's database.
They can be found in the article: Syncing User's ID between Social and SharePoint