You can. Select qtymultipltbynegativeone instead of qty.
But you are looking in the wrong place and making it complex for you. As previously suggested.
Go to sales invoice tab, then at the bottom of the page select Sales Invoice -Lines, then right next to search bar select custom report.
From there you can easily get your required report. And i think developer introduced this feature for this specific purpose to simply it for majority of the user as the old custom reports are too complex for some users.