Comment 5 for bug 920975

Ok, WORK_DIR is fine.

MOUNT_DIR is problematic, the way you've set it it will mount the ISO on-top of your /home directory and after that it will unmount it which will cause headache for you, please change it to an empty direcotry and retry.

Because of that it was unable to create /home/williamt/FileSystem and It should had failed and pop-up error but it didn't happen, did you modified the extract script in anyway? If yes, please don't do so, they are written to stop at given points where if the scripts continue they can harm you OS.

By the way, which version are you using now? As stated in the Wiki older than the current versions available at GitHub.com are _not_ supported (https://github.com/fluxer/Customizer/wiki/FAQ).