Having the exact same problem as Tevashov. The on/off is having no effect.
Just did a fresh 3.5.1 WP install tonight on my domain and after the plugin was not working, had to replace the index.php file with an index.html file I had designed for my under construction page. Thankfully this temporary html file is showing when I go to my domain but I’m not able to build while the site while the index.php file is replaced.
Please help, jkmassel. Thanks!