I've been having this issue for a month. It started with getting the 123 error code when trying to travel to prom. I was only getting that error for prom and not anywhere else. After the latest patch, I never got the error anymore, but now my teen sims don't get the pop-up asking them if they wanted to go to the prom. For a couple of weeks ( NOT in game), I couldn't get them to make a promposal sign or ask another sim to the prom. It wasn't showing up on the calendar either.
I started my game last week, and for some reason, prom is showing up on the calendars again. Sims can now ask others to go to the prom, but on Saturdays, they still don't get pop-ups to travel to prom. Each sim automatically gets a resentful sentiment for no prom invite. I tried traveling to the auditorium right before prom was supposed to start. It's decorated for prom, but you can't do anything, and nobody is in there. Mei Prescot is alive and well. I removed all my mods and cc and started a new game. This did not fix the issue. I saw the laundry list just now, and it says, "Teen Sims will be able to travel to prom even if Principal Mei Prescott is not alive." That's great, but in my game, she's still alive. I hope they look more into this.
I've also been having the same problem with graduation ceremonies! When my teen sim ages up, she automatically gets a "Graduated with Honors" pop-up. She should be valedictorian! I also got a notification in the mail that said that she would receive her diploma. I also tried removing my mods and cc and started a new game, and it still doesn't work.