When scheduling a reporting job with the DateRange filter is applied to show events for the “Last N day(s)/week(s)”, the generated report does not have consistent start time. The timestamp is show at the “Interval" field in the report.
For example, All Logons report was schedule to run with the "DateRange" for "Last 1 day" filter was applied. The reporting job is scheduled to run daily at 00:00 in the Task. For day one, the task took 30 minutes and the generated reports has the “Interval” field value shown as 18/05/10 00:30 - 19/05/10 00:30. On the second day, reporting job waited 1:30 hour for all previous jobs to finish. In this case, the “Interval” field has the start time at 1:30.
The behaviour is by design. This is due to vary time taken to finish the gathering and importing job in the Task.
To have the report returns events for the exact "last 1 day", the reporting job has to be run manually with the filter for the exact date/time applied. The reporting job cannot be scheduled to run.
Enhancement request, ST63883, has been submitted to the Development for consideration to have a static start time to be generated when the filter for DataRange is applied