There are two parameters that you should ensure are set if you wish an employee to see all staff on an Insight report.
The report you are sharing has 'Administrator' Access Type under the settings drop down while in edit mode on the report.
The user who should have access to all employees must have a 'Manager Self Service' System Users account set up. With 'Access all Groups / Departments' ticked under Access Privileges.
📌Note: 'Access all Groups / Departments' setting should be reserved for the likes of HR/Finance Staff who would need access to this level of information regularly. Another option would be to provide an exported excel of the report to required to staff who require it on an ad-hoc basic.