Spawning a utility mob on its side using dispensers sometimes doesn't work

Steps to reproduce

• Build the configuration shown in the image (Note: please build it exactly in that orientation, with the dispenser not facing the body but facing the sides as shown in the image)

• Put a pumpkin in the dispenser and activate it

No iron golem will spawn because the dispenser did not place the pumpkin. However, if you try this where the dispenser is facing the body of the mob, then it will work.