Hello,
That's normal
Cookie "WC" identifies your session with the site; when you login, the server registers that, and even though your session id stays the same, the server now knows that you're logged in (data related to each session is stored on the server).
You can use your "WC" cookie to solve the challenges. You can think of "WC" as a variation of "PHPSESSID", it just has a different name and format.