Same thing happened to me today. I’ve been playing all day and then my sim got stuck in the car entering back into the house lot. I had to restart the game but when loading up my kid is gone. He was in the household photo but not in game. Restarted my game again and now he’s not showing up in the household photo at all but the memories of him are still in game as subject. I have read other threads and people are saying that means his file has likely been deleted. Big bummer as I really liked the kid. Will not be playing the Sims 2 until they fix this as it’s a MAJOR bug.
