SSL report rates as B but indicates "OCSP response is not stapled" and "server's certificate chain is incomplete":
Host is www.blacknight.com. Hosting is Linux shared hosting.
I've generated a Let's Encrypt certificate using the Really Simple SSL plugin for WordPress.
I installed certificate.cert and private.pem via control panel using host's instructions:
Control panel is called Odin Panel. Not sure if it's a known panel or bespoke.
Certificate works (i.e. shows lock) in Chrome, Edge, Brave, and Opera but not Firefox. Firefox displays the following warning:
Secure Connection Failed
An error occurred during a connection to katearbon.com. A required TLS feature is missing.
Error code: MOZILLA_PKIX_ERROR_REQUIRED_TLS_FEATURE_MISSING
The page you are trying to view cannot be shown because the authenticity of the received data could not be verified.
Please contact the website owners to inform them of this problem.
Kapersky is also blocking access in multiple browsers due what it detects to be an invalid certificate.