Hi and thanks for reaching out! I'm an Independent Advisor and a Microsoft user like you. Please allow me to assist with your issue.
Try running chkdsk /f on the drive that is having the issue. It's possible that the master file table has recorded incorrect file sizes. Before running it, backup any important files that you cannot lose.
- Right click on Start Menu.
- Select Command (Admin) or Windows Powershell (Admin).
- Enter "chkdsk {driveletter} /f" (i.e. "chkdsk c: /f" if it's C Drive)
- If prompted"Would you like to schedule this volume to be checked the next time the system restarts? (Y/N)", answer Y and restart your computer.
Upon completion, check the folder size again.
Please let me know if I can help you further!