When updating a web address in Bigcommerce, a redirect automatically is created for the old address.
To remove this redirect do the following:
The easy fix, is change the URL of products that aren’t working. You can go and remove the 301 redirects from Server Settings>301 redirects.
You may need to export them all, remove the ones you don’t want, then reimport the whole list as I saw there is a lot of them.