Hi, I had some problems with single products thumbs and images, but as I found here, the main problem was with new version of woocommerce. But still I have some little problems with sizing of product single image. Somehow the image is little shorter when the mouse is in the frame of the image. wehen i move the mouse outsite the image is getting larger (normal size) if the product is shorter like rings in your demo is dufferent to realise the difference but if it is longer (like models) it is a problem.
Here some css code – in mozzila
div class sxy-zoom-viewport- 470px x 470px- like box
but real width and height must be 470px x 517- it is from the demo of your site.
My second problem is that in products page if some product has more then 1 picture, there is no arrows to change pictures. Mouse hover is working good, only cant display gallery.