Here’s how a couple of people have described the problem on EA Answers at :

“I have a problem with the quest Illegitimate Concern Part 2. I completed the task for Krabappel hosting detention but Bart’s task serve detention is not available in Barts list of available tasks. I cannot complete this quest without it. Any ideas? I tried reinstalling the app, closed the game using the multitask bar, sold and rebuilt the school but so far no joy. Has anyone else had a similar problem?”

“I’ve had the same issue. Krabappel is done with her task but Bart can’t start serving detention because it’s not in his task menu. I’ve inventoried my entire Springfield, deleted the game, reinstalled, sold and bought back the school, treehouse, and Krabappel’s apartments, and completed every task within Bart’s task menu but still nothing has worked. I’ve also emailed EA several times but they haven’t provided any useful information. This is extermely frustrating because this has stalled my progression through the entire game. If anyone has some input I would love to hear it.”

The task was generated by Edna Krabappel, who also monitored detention at the same time (bizarrely, Bart’s detention was for 6 hours, and Edna monitored it for 12). When Bart and Edna both finished, it should have disappeared from Bart’s list of tasks as it’s not one of his regular tasks (his regular 6 hour task is “go to school”).

So, if Edna’s task is no longer in the task bar, and you can’t use it to start Bart, try this – the very next task is for Edna to go on strike. Put the school and her apartment into storage to finish the task she’s on, take them out again, give it a few minutes to see whether any exclamation marks come up, then send her on strike and see what happens.

Anyone having this problem, let me know through here how it goes.