Sideshow Bob is bugged, mostly on Android.
If you can load your town on an IOS device, you can swipe notifications from the top of the device while in the game and get the questline to start. It may take a few minutes. Then you can go in and out of Other Springfield over and over and catch Bob and finish the questline in 5 minutes. Just don't tap anything else but bob.
If you are already on an IOS device, swipe the notifications from the top while in the game, and it should start in a few minutes. But you will have to wait 24 hours between parts of the questline.
If you cannot borrow an IOS device, you can contact EA and ask for him to be placed in your town