We have installed a new type of Large Image presentation for wholesale sites that allows people to see large product images without opening a new window and without leaving the thumbnail page. Since many people turn popups off in their browsers, this will avoid that problem. Also this method is more current.
Below is an image of a screenshot of the way the new Large Image should look. If it’s not that way it is on your site, you likely have a custom thumbnail page so we will need to make a couple of changes in your custom template. Let us know and we will make the change.