I've just (Sat eve) mystery shopped this on both gatelines, doubling back on my Annual Travelcard.
Both barriers stated Seek Assistance, and both attendants allowed me through without question (though the old ticket hall gateline was momentarily unattended). I asked "Could I pop through to Moorgate please?" both times, and they both took a good look at the ticket (Super Off Peak Day Return, London Terminals to Huntingdon, w/ Gold Card).
Perhaps they set the barriers to accept on weekdays, and reject on weekends, to allow for different levels of leisure traffic.