how do you get guests to eat a meal?

I usually have my sims form a group. (click on a sim, actions, add to group) Once everyone involved has a hexagonal marker above their head, I click on the meal and let them have a meal together. It is even possible to click on a chair or sofa and click sit here together and they will all try and sit at the same table or on the same couch. 

Hi! Call to eat should do it... I have a growing suspicion there might be a new glitch related to meals. Yesterday my entire family chose to eat their meal on a sofa instead of the dining table, where the food was served. I know they fixed the glitch where a sim would place the group meal on a coffee table instead of a dining table or counter, after cooking. That one has been fixed, but it's quite normal that one fix causes at least one new glitch... Maybe choosing sfa and "call to meal" no lnger affects non-household sims is the new reality? ;)

You could test if it works in a household with numerous sims + a guest. What happens there might give us a clue.

Hi ...I was thinking you could create an event, ie - Dinner Event. I want to try this myself. See how that works, plus you could end up with a Bronze, Silver, or Gold award. Try it and see how that goes. I will do the same. Also if you put your sim onto cleaning using the 'location' aspiration. When your sim has cleaned enough you will get the end of that aspiration as having a dinner party to show off your clean home. Hope that helps, let me know if it worked. Happy Simming. 

I had to replace all the refrigerators in an apartment complex that I'm playing right now. 

All 6 sims can now eat leftovers in Wilow Creek. This game is seriously broken right now. 😢 

Call to meal hasn't worked for me for months. I use LMSs mod:  Choose who to call to meal, then everyone who is called obey and eat. 

I just went into my game and tried the 'call to meal' method, it worked fine and the other family members joined. I haven't tried a dinner party lately, so i can't say anything about that.