I thought the missing apprentices was just something to talk about and not a quest. I am hoping that they fix the Misc. quest that get bugged often. Tell me to kill a Giant that never spawns, or tell a family that the husband is dead, when you can't even start dialogue with the wife.
TBH, this quest is still in the game. You can find the apprentices, gather what you need. However, you get no acknowledgement from the game. There are a few unmarked quests like this in the game. I don't think it was an error on the devs part to have this be unmarked. It kind of goes to how the college itself operates that no one cares enough to mount a search party. They talk about caring, but never see the need themselves to do anything about it.