EventTrigger touch, detect dragging your finger off a button.

I have made a UI Button with an EventTrigger and my EventSystem has an TouchInputModule.

PointerDown triggers the start of my main characters attack. PointerUp ends the attack.

This works fine with touch on my android builds, but when the user drags his/her finger off the button (but keeps the finger on the touch screen) PointerUp is not triggered.

So I tried adding PointerExit, which also is not triggered when dragging your finger off of the button.

How do I detect dragging your finger off the button?