image doesn't cange when variation is selected

When a variation is selected it loads the image but it only displays it on hovering as for to magnify it. As soon as you move the cursor away, the image goes back to featured image. So it does not display the variation image unless you hover it. Please could you help?
Please have a look here:

https://tree-paintings.com/product/trees-artwork-7618-paintings-wall-canvas-for-sale/

and please select “framed art” and a franme should show up as the image. It only displays it if you hover it.

https://wordpress.org/plugins/yith-woocommerce-zoom-magnifier/