Why isn't the directory size the same as the sum of its children for Windows 10

I have a directory that contains a ton of music that it showing weird file sizes in Windows 10. When I click on the directory containing all the music, it shows 809GB and over 164k files. When I select all the folders and files within that directory to check the sum of their size, it shows only 9.14GB and 2k files. The difference here is staggering.

Though this question is very similar to https://superuser.com/questions/304474/why-dont-the-sizes-of-my-folders-add-up-to-the-size-of-my-hard-drive-in-windows#= it differs in the fact that I am sure I have selected all hidden files, and I double checked the filesize on Linux which confirms that the real filesize of the Music directory is around 9.14GB. I attempted to do the cleanmgr but no change was made to the parent directory's size

Note that the Old Music directory in C:\Sorted Drive\Music\Old Music is 809 yet all of the files in C:\Sorted Drive\Music\Old Music\Old Music is only 9.14GB

Update:
I've change some folder settings to see if some extra hidden system files weren't showing up when selecting all sub directories and files but there was no change.

I've moved the files to different folders and found that the filesize of the parent directory changes to some random value. Even changing the name of the parent directory can change the filesize