I haven't used SpaceMonger in some time because of odd size reporting issues. I just re-installed the latest version today (3.0 Build 1711 / 20181116-11-7FB1BD18) and it totally messed up.

I run this on my Surface Laptop Studio which has a 1TB SSD. It does not have any compression or such on. BitLocker is on, but unlocked.

As you can see from the attached screenshot it's reporting just massive sizes for folder that are just untrue. For instance, the WindowsApps area states 1.6TB. That's 0.6TB bigger than my whole drive. If you look at the properties of the entire drive it's only using 441GB.

If I go to the Statistics view it looks right for some things, and not for others. For instance, Total Disk Size = 952.9GB (right), Free Space = 546GB (right), Used Space = 952.9GB (uhm... no. The entire drive isn't used... look at the free space metric).

Very confusing information. Not very useful.