This is happening to me also and I haven't updated to the newest patch yet, waiting for them to figure out the drag and pull things to trash can and sink bug before I do. When I load the lot my child Sim gets a notification of do I really want to come home, then, if I leave the home lot with any of my other Sims while the child is at school I get the notification they are done for the day even though it is like 9 am in game. Update on this, I finally updated and was able to finish this weeks Natures calling quests and as soon as I did my child Sim was able to stay at school even when another Sim left the lot. Don't know why the event quest not being completed would have affected it, very strange. Will test if same issue happens with the next set of quests when they unlock.
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