I think the issue is coming because of the 3rd party plugins, please deactivate all the 3rd party plugins from the site and activate only theme-required plugins on the site, I am sure your issue will be solved.
Also, please check how it works with the default WordPress theme just to check whether the issue is with our theme or not.
I see the error when the YITH Add-on Plugin is activated. This issue comes up in only Woodmart theme. In the default WordPress themes, both of product thumbnail and image galley work properly.
Please provide the product page URL and describe the action step by steps on how to reproduce the problem.
Please provide your site admin access to the private area.
Make the full backup of your site and confirm the permit for us to deactivate the plugins not related to the theme and switch to the parent theme for the while of checking what may take up to 15 minutes.