Invoice/Purchase Order doesn't display 'Total Quantity'

Invoice/Purchase Order doesn't display 'Total Quantity'

Hi,

How do I show the 'Total Qunatity' in an Invoice or when I export to PDF?

I tried Invoices.Total Quantity, Invoices.Total Qty etc., but doesn't show.

This bug is really annoying that like Sum-of-amount there should be a Sum-of-Quantity? This creates lots of problems in real life as there is not even a work around.