I’m not sure if this is a bug and I’ve repaired my game three times but when my sims go to prom there’s no food and the fountain is empty. I thought there was a buffet table? Also I’ve only received one prompt to vote when normally I’d have two. One for royalty and one for jester. I’ve not edited my lot. I’ve only used what’s spawned from the game itself.
I have found the same a few times where the food and drinks didn't spawn or spawned so late in the prom event that there wasn't enough time left to complete the task when it shows up. I did find that if you click on the table where they should be that there is an option to spawn food or drink for a price. The drawback is that your sim gets charged for it and it gets paid out of the household funds. But I've only had to do that once or twice. When it happened to me, it was right after the pack released so I thought that was the way it worked. But later on, I've noticed that it was spawning on its own and my sim didn't have to pay for it. I haven't had it happen recently. So, you might want to give that a try the next time you go to prom and just click on the table and make food and drink spawn.
As far as I can tell, the tasks you get at prom are generated randomly. I usually only get a task for only one of the votes as an example. There are times when I get no tasks for taking photobooth pics and other times when I get tasks to use the photobooth multiple time to take different types of photos like a solo photo, a photo with your date, etc. I think there are several more tasks for what type of photo you take. There are quite a few tasks for prom from what I can tell that you generally don't see the same ones every time. It's one way that makes every prom different each time imo and nothing to worry about as it was designed to work that way.
Hope this helps.
