If anyone is still having issues making this work, a fool proof way would be to keep the folder path where it is, move the contents to somewhere else on another drive and then create a symbolic link where the previous shader path was.
For instance:
move the whole folder c:\users<your username>\AppData\Local\Unreal Engine to X:\Unreal Engine
Then open a command prompt with Administrator access and simply execute the following command:
mklink “c:\users<your username>\AppData\Local\Unreal Engine” “X:\Unreal Engine”
That’s it. Now all files will make their way automatically to the new path.