How do I get the people who are hungry to go eat?

Had the same problem, and there's no fix that I can tell. However survivors recover more rest and hunger, while playing the game than in idle I've found.

You have to remove the survivors from their jobs. If they are hungry they will go to the cafeteria. Hope this helps!!

Workers who are not working get less hungry, so eating will recover their hunger faster if you have a lot of people hungry, only employ food, coal and cooks. During meal time, remove all the ppl who were working and then add them back. This will add the less hungry people to the work shifts