I only have OS files on the drive (about 26GB) so it only takes a few minutes. I can tell by watching CPU activity. I just ran it twice and CPU is back to 99% idle. No change in symptoms.
Did you notice that it is showing 140.74TB of Backup but the verbiage above the graphic shows the correct numbers?
I accidentally fixed this while working on something else. I saved an invoice from a website to the desktop as a PDF. After attaching the PDF to a mail, I trashed it. I couldn't empty the trash though. I finally executed: sudo rm -rf ~/.Trash/ to empty the trash. Now About This Mac and iStat menus has correct disk usage info?????? 😕😕😕
It was only one file that was a problem. When I attempted to empty trash, I got a dialog box saying that file was in use. I attached it to an email and had sent the email. I'm not sure why it was thought to be in use.