Yes, Windows 8 settings are working fine, regards the Lock Screen.
Playing around, I found the bug (be it Windows 8 API or Decor8) - Decor8 cannot change the Lock Screen if the C:\Users\Username\Documents\Stardock folder has the hidden attribute (the contents are not hidden files and folders, only the top folder).
It would be good to fix this, if possible, because this is not a user document folder, but an application data folder that belongs in %APPDATA%, and so, like other numerous folders that clutter up the Documents folder, it is natural to want it hidden to preserve the usability of the Documents folder. Presuming it is not the Windows API that is doing this.