How does Anspress authenticate users?

My custom homepage still gets inserted in the ‘Write your answer’ form when I try to answer a question as a logged-in user – see my previous question.

I guess Anspress checks if the user is logged in before allowing to answer a question and that somehow that check fails even though the user is definitely logged in.

And then something in my theme redirects to the homepage with the login/registration form – although instead of redirecting, Ajax inserts it into Anspress’ answer form.

How does Anspress authenticate users? Is there a way to remove authentication? For troubleshooting or maybe I could just rely on authentication in my theme.

I have a multisite installation with a custom registration process. Does Anspress even work with that kind of set-up?