My mates daughter has a Macbookair dual boot win 10 machine 128gb. She was trying to install something for school and came up with a full HDD. After some searching i narrowed it down to the WinSxS folder whilst looking to see if it was the Windows.old folder that was causing it. ...but there is no Windows.old folder to be found. I've tried the winsxs cleanup cmd (Dism.exe /online /Cleanup-Image /StartComponentCleanup) which failed to find or remove anything, disc cleanup run as admin finds no option for old win installs/upgrades etc and only removed 4mb. How is it possible that over 40gb can be hiding in that folder? She is set up as admin, hibernate is off, backup is off, hidden folders etc off. She has another issue as well, when we first started looking at it we went to remove a program (3dviewer) as she said she has never been able to uninstall anything. The uninstall pops up, click it, it goes away, nothing uninstalls. Her pc is clean otherwise, no vids, movies, games, large files etc, she uses it solely for school.
edit- just got him to send me a pic via messenger of anything called installer in that folder and he said these came in at about 6gb each
Those look like double ups, same file names and times. Seems like the culprits, some old left behinds that haven't been cleaned up by windows for whatever reason?