The window disappears after the first frame has been rendered with vorpX being active, so if it disappears hooking into the game has been succesful and there is no need to install a hook helper. The window is not supposed to disappear if you exit the game before vorpX has detected that the first frame has been rendered.
The window does not always disappear after the first frame has been rendered. I’ve seen it still there on game shutdown numerous times. It’s minor, doesn’t affect anything, and closes after a second or two.
Actually, I don’t think the window pops up sometimes until a game is closing, so rather than not disappearing, it appears and then disappears on game close. Anyway, it’s just a minor annoyance.