Used to get event invites from NPCs (birthdays, playdates) but don't anymore?

I remember perhaps a year ago when I was playing my sims would get invites to events from their NPC friends—sort of like getting asked on a date by an NPC, but there were more events, like birthday parties, playdates for kids, etc.—but at some point I just stopped getting these. I thought it could be something that changed in my game or perhaps it was just patched out, but I did some searching and it looks like some folks get these all time, some have never gotten them, etc. and it doesn't seem like there's any pattern to it. It's not a big deal, but I thought it was kind of cute and realistic that one might get invited to a friend's birthday party or something, and since it seems to happen for some people and not for others, I wonder if it's a bug or some issue?

I'm on a MacBook Air, I keep the game updated, and I do have a few packs and mods installed (MCCC), but if I'm remembering correctly, I stopped having these events when I was still playing vanilla with just the base game.