membership 2 pro - after registering and paying, users are not becoming members of the plan

Hello. I went all the way through the sign-up process as a test user, and paid for a membership with 2checkout, but I don't end up becoming a member of the plan. As in, if I go to the login page it says I'm already logged in. If I try to go to a page that I should have access to, access is denied.

In my dashboard I can see that my test user is added to "users" in wordpress as a subscriber. But if I look in Membership, the user isn't there.

If it matters, I have a shortcode on my register page so people don't have to go through both "select a membership" screens (it skips the first one). [ms-membership-register-user membership_id='370']