I had the exact some problem as you-- I'm using MV, and pressing F9 just gets the variable/switch debug menu to show up.
... Then I realized something-- I didn't go into the menu before pressing F9. (In fact, I don't think you can even open the variable/switch debug menu using F9 if you're in the menu, so odds are good that you forgot to enter the menu before pressing F9 too.)
(The plugin works flawlessly for me now.)