Re: Baby doesn't appear after being born

@simonvl1  Try evicting the household and placing it on a different lot; see if the baby appears then.

If that doesn't work, you can try splitting the household, to see how many sims the game thinks are in each new household.  As in, keep adding sims through CAS until the game says no again, and you'll have your answer.  You don't need to save your progress; the idea is to isolate where the phantom sim is and go from there.