PointerEventData.hovered blank when used with Right mouse button drag.

I am not going to Waffle, so this will be short and sweet:

using the EventSystems: "public void OnEndDrag(EventSystems.PointerEventData eventData); "

When end dragging using left mouse, the eventData.hovered is populated with the GUI elements underneath the mouse.

But hovered is empty when end dragging with Right mouse. I have tested that OnEndDrag calls with right mouse with a simple Debug.Log,

Can anyone explain why? am i overlooking something or does the hovered explicitly populate for left mouse?

kind regards, B