I have been having the same issue. I just upgraded to 1.2.9 but it hasn't resolved anything.
I've attached a link to a screen grab, so you can see the settings I'm using, but basically, when I'm in test mode, the screen darkens after the criteria are met, but no pop up appears. If I click anywhere in the screen, the page is active again. I am using the latest version of Chrome in Win 7. If I take test mode off, I don't get anything. I get the exact same behavior in IE, but in Firefox I don't even get the dark screen in test mode.
I have disabled ALL plugins and nothing changed. I've also attached a screengrab of my plugins.
I'm at a loss where to go to try and fix this one. Is it a theme issue? A browser one? Or does it lie within the plugin?