Steps to reproduce:

1. Open the attached project
2. Open 'EventSystemBug' scene
3. Notice that three sprites are rendered corretcly according to the 'Sorting Layer' properties set
4. Play the scene
5. Hover the mouse on these sprites

Expected behavior: OnPointerEnter and OnPointerExit should be called with the same order the sprites are rendered.
Actual behavior: OnPointerEnter and OnPointerExit functions gets called without taking sorting layer into account.

Workaround: Place all the sprites in the same Sorting Layer and change their 'Order in Layer' values to match the wanted rendering result. Notice that now the mentioned functions get called as expected.