Winterhold Radiant Quests Won't Start

I understand that when a magical skill such as Destruction reaches 90 you are supposed to be able to receive a special radiant quest from the master that skill (Faralda, in the case of Destruction) where the rewards are more powerful spells in the school. But though I have achieved a skill level of 90 or more in several different schools of magic, I canno get any of these quests to start. For instance, my illusion skill is 98 and the master of Illusion is Drevis Neloran, but no matter what I do or where he is I still can’t get him to offer me the quest. The same is true for Destruction/Faralda and and the other schools of magic. Is there some other requirement I don’t know about, or is there a console command or some such I can use to get these quests started when my skill levels are 90 or more?