I’m still looking into this. For some reason something has changed on WooCommerce’s end which stops us from being able to reset the image zoom when you change the variation. Hopefully I’ll be able to find a way around this. Will keep you updated.
Just to let you know I implemented a fix for this on your site, but it hasn’t gone through to your CDN – can you please push it up there so that we can see if it works on your frontend?