An update! After tinkering a bit we have found that adding Quick Filters to the default queues installed with OSTicket does not work reliably BUT if you create a new custom queue, the quick filters seem to show up there consistently. For example – we ended up creating a fresh “Open” queue, retiring the one installed with the system, and now quick filters work there like a champ.
Hope this is helpful for anyone else interested in having this function available.