Input problem within the challenges heavy bag

In UFC if I go to the challenges menu , standup, heavy bag, challenge #3, first hit x to begin. The lesson is called alternating hands.

now three triangles are shown as I am playing on the ps4. No matter how many time I do this I get the same result after pressing triangle 3x only 2 presses register.

If I wait and press the button again or 4 times it will register but never after 3. It is frustrating as can be and the result never changes. Help ...