Issue
Users with access to reports and/or widgets on a dashboard can view the counts for data that they would not normally have access to due to ACL restrictions on the source table.
A user viewing a dashboard containing reports or widgets for a table they are restricted from viewing by ACLs can still see the data on the report/widget. However, when they click through to the list no data will be returned.
Release
All versions
Cause
Aggregate reports do not evaluate ACLs when processing data to be displayed.
When you click through to the list, the data is not displayed as expected due to the ACLs being evaluated for each record displayed.
Resolution
This is the expected behavior of aggregate reports. As a solution please review report_view ACLs.