When looking at the number of viewers in the Top Posts table from the Content Overview report, the number of viewers does not match the number seen in the Post Performance report for that piece of content.
- Studio | Insights _ Content Overview report
It is expected that different reports will return a consistent number of viewers for the same piece of content.
There is currently no known workaround or resolution for this issue. Please check the current status of this issue on the Known Issues Tracker. (Issue ID: ME-3008)