You’re right, the id isn’t being set. By default we use REMOTE_USER here. I’m not 100% sure about shibb. It seems like it should be returning your email address in that variable as a default.
Did you happen to change user_env in ood_portal.yml ? This variable (user_env) is what instructs apache to pass into the regex. Mostly REMOTE_USER is fine and folks don’t have to set it.
From the docs here, it doesn’t see like we need to change it. I’d turn debug logging on for your shibboleth auth module and see what variables it’s setting (and if REMOTE_USER is one) when you authenticate.