YTD Balances Report - Download a CSV for all employees

I have a customer requesting this report to be amended due to misleading figures showing for leavers, irrespective of what Schedule, Period is selected or when this CSV file is downloaded.

For example, if an employee left 6 months ago, but you download the YTD Balances report for all employees today, values still show in all columns that display 'This Period' Values.

The customer would like this amending so all leavers that show on the report have the correct values in the correct columns.

Thanks