Database purge and missing reports



I set up a DB purge policy to delete old visitor records older than 90 days and old reports after 12 months. I chose to keep basic metrics, monthly and yearly reports.
We are running Piwik version 2.1.0. There is an archive cronjob running every hour.

/usr/bin/php /var/www/ --url= >> /var/www/

After running the purge operation I cannot see any data older than 90 days on my site dashboard.
Any help regarding this would be appreciated.