To reduce the performance impact of generating sales reports, Magento calculates and stores the required statistics for each report. Rather than recalculate the statistics every time a report is generated, the stored statistics are used, unless you refresh the statistics. To include the most recent data, the report statistics must be refreshed before a sales report is generated.
Refresh report statistics
On the Admin sidebar, go to Reports > Statistics > Refresh Statistics.
In the list, select the checkbox for each report to be refreshed.
Set the Actions control to one of the following:
Refresh Lifetime Statistics
Refresh Statistics for the Last Day