sorry this is an issue for you. Perhaps you should contact EA and explain your situation. No guarantee but maybe they can place him in your town for you?
The game has code on top of code from the years of it growing and evolving. It may not be a simple fix. Let me pass this onto to EA again.
At one time I knew the month and year he quit working properly. When I have time I'll see if I can find that again. In the meantime you still may get him, he does appearer
just no one knows how or when anymore. Good luck to you!
October 2017 - last edited October 2017
@Nazmaster1999 Unfortunately this is only a solution once you actually have the quest line appear in your task book. A lot of players do not get the quest line appear and that is where the problem lies. You can catch Sideshow Bob as many times as you want per day in ‘Other Springfield’. I have written a tips thread for the EA forum in which I have added information about Sideshow Bob.
There is a quest line called 'Flaw and Order', parts 1, 2 and 3. Once the 3rd task is completed you will get Sideshow Bob as a playable character. You may need to be patient waiting for the quests to appear, as they come up at random and are not linked to any particular level. I had to wait until level 336 to get SSB in my newest town.
The answer I get is complete other tasks and this might pop up. But that's not very helpfull to me as I don't have the money to complete Monty's Money Mountain nor time to micromanage the Springfield Heights.
If you play on an Apple device, then there is a way to trigger the quests.