Currently the time entry dashboard shows results for all projects and employees in your selected filter criteria. On some client instances, the employees are assigned to different business units.
To be able to generate the report for a specific business unit or department, you need to have this in your personal filter, which means that the report needs to be run separately for each business unit or department.
By adding the grouping (repeater) on the business unit or department level, the report can be executed once, and therefore is much easier to use on a global level.