You may have not noticed that the links to self-register for an assessment and to actually take an assessment are different. Unfortunately, we've seen situations where an assessment user tries to return an in-progress assessment using the self-registration link. This results in the user unexpectedly seeing a registration form and not his or her existing session.
To address this issue, we're now using a browser cookie to save when a user has started an assessment session. If a user accesses the self-registration link in the same browser, he or she will automatically be sent back to the in-progress session rather than shown the registration form.
In the event that the user re-registers for the same assessment with the same email address, TAP will return the in-progress session (and not create a new one).
Hopefully these small changes makes the assessment experience that much easier.