This bug was fixed in Patch 1.97.42/1.73
Parents want to interact with their infant/toddler but there’s very few interactions available and you have the option to introduce yourself to your infant/toddler.
Parents that have the trait Beloved (Friend of the World aspiration) seem to be strangers to their own children although the relationship is high.
There are reports of this happening to Sims without the Beloved Trait. so there might be other triggers.
Introduce the toddler to the parents. After that there shouldn’t be any more issues with interactions.
It’s a bit more complicated to be introduced to an infant since the option is grayed out if there’s no other caregiver that doesn’t have the trait on the lot that can introduce the infant to the parent.
Hire a nanny and let them introduce the Sim if there’s no other Sim available.
If you have many children since you’re for example are playing a 100 baby challenge it can become tedious to have to introduce every single infant to their parent. You can also just remove the trait from the Sim.
Make sure the Sim is active, then use the cheat traits.remove_trait trait_Legendary to remove the trait.