It’s 2 active WL per membership per UY, not calendar year. Could this be it?
I called once and the CM said, you already have 2, but I reminded her that my UY was August and my other one I wanted was after August 1st.
Also, if you want it to replace an existing reservation, only the 2 for the membership with the reservation can be set up that way, If you put waitlist in place on the other memberships, they would be for a new reservation.