Open
Courses -> [COURSENAME] -> Reports -> Logs
change in dropdown "All actions" into "All changes" and generate the report.
You will still see the entries of the report generation, although it is not a change.

This happens because query parameter modaction=-view
which results in filtering all entries from log where action does not contain word 'view'. But for the reports mdl_log.action='report log', 'report stats', etc. They do not contain word 'view'.

This means that the log report is not empty even if there were actually no changes to the course.

In order to solve MDL-25454 I need to check the log for any changes during the last month and am supposed to use the same algorithm as change log. At the moment I treat report generations as the changes (as well as report itself). When this issue is resolved, please come back to MDL-25454