Image Gap in product page

Hi,

My website is almost finished, but one problem is raised. It’s about the single product page. The images that we uploaded are the same size, which is 800 x 450. All the appearance of single product pages are no problem until yesterday. We want to have final check before launch the website, we find that some of the single product pages are suddenly showing lot of white space between the images bar and the main image. However, some of the pages are no problem. What should I do?

Thanks so much.

Best Regards
Eric