Joystick + Aim Crosshair Custom Controls Resetting When Riding a Horse

I loaded up my survival world after playing around with the joystick + aim crosshair customize controls, and when I rode my horse, the buttons reset to their original places and sizes as before customizing.

I tried recreating the bug on a creative world with a spawned in horse, but the buttons didn't reset when riding, with and without a saddle.