Not a big bug but holding down right click on a single item [raw meat in this case] and moving your mouse to a stacked item [sand in this case] will cause the stacked item to show the single item [raw meat] in the middle.
The stacked item does not have to be directly beside the single item, as long as you hold down right click on the single item and move to a stacked item somewhere in your inventory, this bug will occur.