Hi @miemie
The site is completely test and there are no other plugins on it. I installed the WPClever theme, but it didn’t help. I posted new screenshots and videos from WPClever https://disk.yandex.ru/d/SKoMw5H3r_ZkGQ/WPCstore
I can provide access to the site or try to install a clean wordpress, woocommerce and your plugin. After that, create several test products and set the settings as in my screenshots earlier. I am sure that the error will be repeated.