Rolled chapatis come back eaten, rice and dal come back full. So it's the time, not the food?

For two weeks I've been packing my 9 year old's lunch in two forms on alternate days. Same dal, same sabzi. On rice days the box comes home half full. On days I roll everything into chapatis she can hold in one hand, it comes back empty. Her own explanation is always that she was talking or everyone went to play. So I don't think she dislikes the food. I think lunch and play share one short break and she eats whatever can be eaten while walking. I could just pack rolls forever. But I'd rather know whether the break itself is the issue before I build every meal around eating on the move. Do your children's schools have a set eating time before they're let out to play? Wondering whether that's a normal thing to ask the class teacher about.