IPointerUpHandler not triggering

Today I tried implementing that Interface. But when I release the mouse button, the event is not triggered. However, when I implement the IPointerClickHandler, the UpHandler starts working … Is this intended ?

E: When I press the mouse button when over a different gameObject than the one I release the button on, the IPointerUpHandler event is not triggered either.

The OnPointerUp(PointerEventData eventData) is called if the eventData.pointerPress is set to the same object prior to calling OnPointerUp.
You can see my answer here