Ideas
This is happening to my sims as well. It is random and not limited to a specific age group. It has happened at their homes and in a vacation rental in Granite Springs. My workaround is to travel with the affected sims to a public venue and then go back home and so far that always resolves the problem. When it happened in Granite Springs at the vacation rental, I traveled the sim to the forest lot and the back to the lodging. The issue is very sporadic and it doesn't just happen out of the blue. Meaning if a sim is able to eat, they're able to eat. I feel sure that the problem arises after they travel somewhere. Like they were fine before leaving on vacation, then when they arrived in granite springs i noticed the older child could not eat. took him to the forest and back to the rental and he was fine. These screenshots were taken after the vacation was over an they arrived back home. I have had this happen in the Bailey-Moon family as well. To both Thorne and his teenage son Orange. Thorne goes to work and Orange goes to high school and occasionally I would take Thorne and Octavia out to a public venue. They did go on vacation to the same vacation rental in granite springs that all of my households use and I don't remember it happening to them there. So the only thing I can put my finger on so far is that in some way the issue has something to do with traveling.