Wither effect resets instead of stacking

DEVICE: Samsung Galaxy Tab A

The Wither effect resets instead of stacking when hit by a Wither Skull.

STEPS TO REPRODUCE:
1. Spawn a Wither.
2. Let yourself get directly hit by two black wither skulls.
3. When the second one hits, instead of resetting the effect to max, it is supposed to stack on top of how much time is still left.

For example: On hard (max is 40 seconds for wither effect), if there are 20 seconds left from the first hit, right now, it resets it to 40. But it is supposed to stack and end up with 60 seconds if that scenario were to occur.