The author of the support ticket sent me a link to their website using the plugin’s contact form.
After checking out the front-end of the website, I can confirm that the main product images don’t have their alt attributes changed by the plugin.
This is probably due to the way your WordPress Theme is rendering the images.
For example, the related product below have their attributes changed as expected.
This means that the plugin is most likely working correctly on your website.
Note that the plugin cannot work with all available WordPress themes.
It depends on a WordPress filter being used to display the product images.
Big themes like Divi, Avada, etc. use the appropriate filters and hooks and the Woo Image SEO plugin will work with them.
You could try contacting the theme’s author.
If you do, make sure to mention that the main product image isn’t using the recommended filters.
More specifically, we need the
I hope this helps.