emailLinkSignIn not working

When setting `firebaseAuthConfig` (to be given to `StyledFirebaseAuth`), if `emailLinkSignIn`
is set and `url` inside it is defined, the sign-in is not successful, in the sense that clicking the email link won't sign the user in (and the `signInSuccessWithAuthResult` callback is not invoked --- this is where I set cookies and only if the cookies are set can a user be identified as having signed in). If I don't set `emailLinkSignIn` then everything is working fine.

What could be the problem, and how could it be fixed?

P.S. Just a note that when I have `emailLinkSignIn` set, I do see the `url` is visited but somehow the sign-in is not successful.

Another note: if I'm already signed-in, then including `emailLinkSignIn` and going through a new sign-in (an email is entered, the link is clicked) will send me to the `url` inside `emailLinkSignIn` successfully.

Updated: I've found out that if `url` points back the `auth` (it's where I ask for the emails) then it will be a success. I don't understand the current behaviour or if I'm using it correctly. Any help will be appreciated.

Thanks!