My server runs Nginx not provided by cPanel and the AutoSSL log says the certificate is valid, but I have an SSL error in my browser.
Often times third-party webservers need to be manually reloaded or restarted in order to load their latest configuration, so the certificate you're seeing is just the old one.
Have your systems administrator fully reload or restart the Nginx service. If the issue is not resolved, try switching to Apache to see if the issue still occurs. If it doesn't, you may need to review your Nginx configuration.
Please note that cPanel L.L.C. does not support Nginx other than ea-nginx which is still currently experimental and not recommended for production servers.