simple "false" in visibility field – sometimes doesn't work

I have a really simple menu, and just wanted to temporarily disable a few items by putting false in the visibility field, I tried just a parent and then the parent and all its children.. for some reason the menu disappears like it should, then it reappears when clicking other menus. I’m not sure if it’s a bug? Has anyone else seen this behavior? Other menu items in the same page also have false in the vis field and they stay hidden.

http://wordpress.org/plugins/menu-items-visibility-control/