Thank you – as far as I can see, the custom permalink for that specific product does not seem to be stored by my plugin. Do you possibly have another permalink plugins enabled on your website. Please send me the screenshot with the “edit page” where the URL ending with .html is displayed?
Thank you! I think that the source of confusion here is a bug introduced in one of the latest updates. The canonical permalink displayed next to “Permalink Manager” button should not display the default permalink, but instead the actual permalink which is displayed under “Custom permalink” field. This happens because the plugin has not generated and saved the custom permalink for the product, defaulting to a “future” permalink (for preview).
Happily, to fix this all you need to do is simply update that post. The “Default custom permalink” field indicates the correct URL ending with .html and “auto-update” mode is turned on, so the correct permalink should be set then.