Incorrect Grand Total

Hello Everyone,

I've a scenario where I'd converted my negative number into the postive number but when I try to sum up this converted negative number with the positive number the grand total that I'm getting is wrong. Because since I've converted it to a positive number the grand total should increase instead what it's doing is still showing the difference number. And lastly when I apply the filter it's showing 0.00 intsead of showing the correct grand totals.

Below are the screenshots provided for both the scenarios.

Please help in this matter.

Thanks & Warm Regards,

Harsh