We have run into 2 issues now when we have modified a dining ressie from dinner to a lunch time. In both cases, we have gotten a reservation confirmation for the new time but both the app and My Disney Experience still showed the old dinner time which prevented us from making new dinner reservations for that evening. The first time was not a problem as we opted to dine in the room but the second time necessitated an hours worth of wait/talk time to get a dinner reservation through the phone reservation system. NOT very magical.