@IndiiAna That is a bug, and is on the new Laundry List so hopefully fixed soon :)
https://answers.ea.com/t5/Bug-Reports/OPEN-Parent-needs-to-be-introduced-to-infant/td-p/12382854
It seems to happen more often with parents who are famous or have the Beloved reward trait from the Friend of the World aspiration. So in the meantime, before it is fixed, you could try temporarily stepping your sims out of the spotlight or removing the Beloved trait with cheats, if that applies to your sims.