It seems that in 2.8.3 (also confirmed in 2.7.0) is bug concerning SiteSearch plugin used with scheduled reports.
It results in proper sending of email report (no error in archiving output), but file delivered is empty and has invalid name (email title "Report Example - " and file title is also "Report Example -.pdf").
On the other hand manual sending and download causes correct content to be generated.
Steps to reproduce:
After adding some other metrics to this report it starts working fine.
Also website experiencing this prolems has some data in SiteSearch report
Please let me know if I can provide any further information regarding this issue ?
Should be fixed