Hi,
I recorgnized that the File System Lock is only working on the public_html folder of the main accounts domain.
If a User has more domains they are still unlocked.
eg:
Main Domain main.com -> there is the public_html folder, and it gets locked
All other domains which are in a seperate folder for each domain, they doesn't get locked.
So the File System Lock is not working properly in my opinion because only 1 Domain of many gets locked