ShowAsContext For GenericMenu Goes Leftwards

I'm using GenericMenu to show a context menu that has submenus with the ShowAsContext function, but for some reason most of the time the submenus have a tendency to display leftwards instead of rightwards. Is there a way to control this behavior? At the very least, I'd expect sub-menus of sub-menus to display in the same direction as their parents but sometimes I get them going left-right-left-left or other weird patterns. Apart from this baffling issue, the function works great, so ideally I'd like to stick with it.