I did a search and found a thread from 2006 about this, but it didn't answer the question. When my Sims go to a restaurant on a date or alone they get seated and can order food, but the wait staff never serves them. All the other Sims who are dining get their food, just not mine. I have all the EPs and SPs. I also play a Medieval game so all the food is renamed. I haven't tried removing that default yet. I have tried 2 restaurants so far. One of the pre-made restaurants that is found in Downtown and one that I made in my neighborhood. In the restaurant I made I did use the community stove. I have watched as my Sims order the food, the cook makes it and sits it next to the stove, then a server picks it up and, I think, delivers it to another customer. My Sims have to pay for food that they never received or ate. Can someone help me?

I think you'd have to make a safe backup of your neighbourhood, and then do a 50/50. Test with the most likely mods removed first.
Game Help:Finding Problem Custom Content^wiki

If no Sims got food served at the restaurant that is certainly what I would have done before posting. I can't think what mods could be causing this, but since I have my mods and CC organized it isn't the end of the world, just a slight headache.