the jumping mechanic seems to be broken
Work for me? Press space (or the button you have set in settings as jump) on the ramp. If you miss even a little(1px over the ramp), you will miss the jump. If you press too early, the jump power is low and can feel like you did not even jump.
The GIF above, where the player's time slows down on the ramp, is due to the player having used the "neurofocus" item. Normally it goes fast!