I've never had this problem. How fast are you clicking? Does it tend to select it better if you click longer?
I think there used to be a bug where if you clicked and lifted the mouse on the same frame, it wouldn't select the element. But even doing tpt.setfpscap(3) this doesn't happen for me, I can't reproduce it.
I can consider finding a way to change it, but right now you need to do a full click to select an element. It isn't selected on mousedown, it is selected on mouseup. If you don't do a proper mouseup, then it won't select.
Every button is the same, if you move the mouse off the button it cancels it
Perhaps you could make it so that if the mouse button is released maybe 2 or 3 frames after leaving the menu, it will still count as selecting an element.