Hi @rotipom,
Sorry that you’re having that issue, yes we do help by investigating what could be possibly causing the issue, and if it causes by a 3rd party plugin then that is something that we can’t go further with, please provide us the site URL and login credentials in a secure note so we can take a look.
In the meantime, please do the common troubleshooting guide provided here, skip the things that you already done, but please make sure you clear and deactivate your caching and CND features for awhile, since site inconsistency issues are most likely related to caching.
This is the only time I see this issue so besides caching it’s more likely it’s your shipping-zones configuration or site setup. A plugin conflict is still a major possibility. And please make sure your WooCommerce is still in version 4.0 because that is the latest supported version.
It would be best if you have a Staging Site so we can do the troubleshooting without affecting your live site, you can also use this staging site to test plugins.
And by the way since we are not familiar on the process on your site, please provide us step by step guide on how we can replicate the issue (e.g. what product should we add to cart and what country, what shipping method should we choose on checkout)
Thanks,