Mobile movement buttons not working

The inner part (closer to the crouch button if crouch and jump buttons are not swapped) of mobile movement buttons (forward, backward, left strafe, & right strafe) are not working. While the farther outer part of the buttons work completely fine.

As shown in the video, when I touch the inner part of movement buttons, the game detects it but my character won't move. When I touch the outer part of the movement buttons it still works just fine.