Enter the URL that is used to access your publication. If using a subpath, enter the full path, https://example.com/blog/ . If using SSL, always enter the URL with https:// .
I had this issue because when adding a redirect from www to the naked domain I had incorrectly added a line redirecting from naked domain to naked domain in the file mywebsite.com.conf in /etc/nginx/sites-available when configuring SSL. This resulted in an infinite redirect loop.
Updating this and then confirming the config change with sudo nginx -t and reloading with sudo nginx -s reload resolved it. I am using cloudflare so I also switched off proxies, switch on development mode, purged the cache and even after clearing cookies and browser cache I wasn’t able to view the site only in incognito would it show again. I’ll wait a bit for it to show again in the browser but I’m fairly satisfied that this is now resolved.