I'm in the same boat. I've run it three times on a Windows 10 machine, and until I turned off VSS, it kept chewing up more & more of my drive space. It's beyond me why disabling VSS isn't the default on a Windows 10 machine. When defragging the first time, I went from 70GB free to about half that.
Even then, once it was done, it claimed that I have 13 files in 40 fragments, occupying ~ 6GB. If I immediately run it again, it claims I have 200 fragmented files in 570 fragments, occupying ~6.1GB.
Back before Windows 10 came with its own defragger, I've used a variety of commercial ones, and this is by far the worse. I can't recall any others that couldn't even provide consistent results over a span of 5 seconds. I find it very hard to believe that even Microsoft could fragment my drive that much that fast.
Time to uninstall...