When a product has a couple of color squares and a couple of image squares the main large image does not change when clicking on the image squares, it only changes when a color square is clicked.
It works only if it's the first thing that is clicked after a page refresh; meaning it works only if you click the image square first, but stops working after clicking the color square.
There are images associated to all squares and SKU does change when any of the squares are clicked.
This occurs on the default NOP theme as well as many the Prisma theme.