engine - 6:00 pm on Feb 22, 2013 (gmt 0)
While trying to speed up its iOS and Android apps, Facebook accidentally stripped out too much data about news feed posts by Pages. This caused Page Insights to be misreported, leading admins to believe their posts reached fewer people than they actually did, in most cases. Bug fixes are now rolling out and accurate data will flow into Page Insights starting Monday.
Facebook Critical Bugs Resulted in Months Of Page Reach Report Errors [techcrunch.com]