Why doesn't my game update on Android Tablet unless I'm clicking the screen?

I'm making a tile-based click to move game on tablet where the player's parent is always the tile the player is standing on. I want the player's parent to always be blue, so I have this in Update: transform.parent.GetComponent().material.color = Color.blue;

It works as it should on PC, but on tablet it only works if I'm actively clicking somewhere on the screen. I'm using NavMeshAgent and my character moves to it's destination even if I'm not clicking, but the color of the tiles the player walks across doesn't change unless I'm clicking somewhere on the tablet. It's like the game doesn't update unless I'm inputting on the screen?

Does anyone have any idea? Maybe there's a setting for it on the tablet itself? Thanks in advance.