I didn't reach the end, it was too hard for me... il try to explain the problem with the jump
Imagen you place your hands on a keyboard, You will have fingers on the left, down and right buttons.
Now say you want to press the up button, You will move the middle finger from the Down button to the Up button.
But in the movement what you also do it stop pressing the down button, And when you try to activate the high jump you need to press Down and then Up, So when i move the finger to the Up button it thinks that i stopped the jump, since the down button isnt pressed anymore.
Hope it helped.