Sorry for the obvious question — did you try entering the infirmary the next day after you talked with Seraphina and her assistant?
I went back through and I believe that it was a visual bug because I completed Zahera's route and remember all of it, so I'm pretty sure that the route had already triggered and I just forgot, and the tip was from earlier in the route and somehow got displayed rather than the end route tip that usually tells us to be patient and wait for the next update