A discrepancy between statistics in AWStats on Plesk and PBAS when Nginx activated on Plesk.
Webalizer does not update daily statistics.
This is Plesk internal issue with ID #PPPM-1299 that was fixed in Plesk 12.0.
A general solution is to upgrade Plesk to the latest Plesk version , as the issue is related to Plesk 11.0 and older versions.
Alternatively, apply a custom fix for Plesk 11.0: download and unpack a patched copy of statistics_collector utility. Place it to