When brushing suspicious sand using touch control "D-pad & tap to interact", the brush animation does not work.

This could be because when using this mode you need to tap continuously to "brush" the block as holding down on the block breaks it.

The brush animation works when using joystick control form as it's possible long hold on the "interaction button" (or whatever it's called).

This could also be impacting iOS platform as well but have not tested.