Image is hidden by another one when scaled

I am trying to scale an image on mouse click. When I scale image 4, it hides images 1 and 2(as needed), but for some reason it doesn’t hide image 3.

All the images are in a 2-row Grid-Layout.

I tried to use Sprite-Renderer to make image 4 in a higher sorting layer than image 3, but it didn’t work.

Could you upload a picture of the hierarchy ? A picture of the inspector of the grid object and one of images object would be useful too.