If you log into Facebook and bring up one your Facebook Pages today, you’ll see a “Page Insights Update” box that states, “We fixed some reporting issues in Page Insights. Learn more.” The announcement from Page Insights says that, “As part of our ongoing investment in Page Insights we recently completed a comprehensive engineering audit of the product. During this audit, we uncovered bugs that impacted impression and reach reporting.”
The announcement goes on to explain that paid and organic content delivery was not affected, just reporting. In other words, followers and Facebook users were able to see your stories or ads as intended, but Facebook failed to accurately tell you exactly how many times those stories or ads were actually viewed.