I have also had this issue with my game. It came time for my Sims' birthdays so I aged all three teens up (two are supposed to graduate) and it gave me a pop up with one of them saying a graduation ceremony would be scheduled on the calendar in the coming days. They aged up on a Friday and I waited all the way until Monday but no ceremony, not even showing one on the calendar. I have tried several things to make it work. I tried not throwing a birthday party, I tried turning off Get Famous which a different forum suggested, I tried deleting all the holidays from my calendar and nothing is working. Thankfully I saved before aging them up (because I wasn't sure how the ceremony works since the game is new) but now I can't play the family until the bug is fixed or some sort of solution is thought of. The only other thing I can think of that I haven't tried is allowing them to age up on their own, no cake or anything, but I've lost patience with this right now to try it if someone else wants to. I should also mention I have no Mods in my game either.