The reason this happens is because of the way High attacks are implemented. High attacks straight up can't hit crouching opponents no matter how big the hitbox is. The easiest way to see this is Sindel's air scream ball if you mess with the pc version files. It goes diagonally down but no matter how you aim it, it won't hit a crouching opponent. Ball Roll is not a crouching attack so high attacks with low enough hitboxes will hit her. The only ways to "fix" this would be to make Ball Roll count as crouching, nerf the hitbox of that scorpion normal, or specifically make Ball Roll immune to that normal. The first 2 options are not very good choices and the last one is weird. This should probably just be left alone.