Let’s separate these 2 builders and the errors related to them:
If you edit the multiple headers you are redirected to the blog page. You don’t have posts, so your blog page displays: no posts found. That’s normal because you really don’t have any posts. We’ll try to change the redirect to the home page once you edit multiple headers in the future update.
Single product builder
The single product builder has some issues with the redirect. It looks like the redirect to a single product page is blocked because of something. If we disable all the third-party plugins and clear the cache it works but once we start to enable third-party plugins it stops working. Do you have any blocking of the redirects in your server settings or in the Cloudflare settings?
Also, we can’t check the shop page because it displays a lot of errors related to cache and CDN https://prnt.sc/1bPHCHi2Mrla + I see errors related to your server limits https://prnt.sc/bbsz_VXuuQK_
Could you fix the limits error in your server settings and also temporarily disable Cloudflare? Because maybe some CF settings cause the errors.
One standard license is valid only for 1 project. Running multiple projects on a single license is a copyright violation.