I am having a similar problem, but slightly different.
I play several different households at once. If a sim I am playing visits another one of my sims who happens to have a baby at the time, the parents do not take care of the baby at all. I get a notice that the baby is starving, but the parents, who have maxed parenting skills completely ignore the baby.
Yeah, this is a thing I've noticed. I used to use MCCC story progression, but I also play rotationally, and either way unplayed parents ignore their crying babies. It leads to some funny moments:
My Super Sim and her Mom, who are doing the Nerd Brain Aspiration: Hi! we ran out of things to upgrade at our own house... oh, hang on, we need to Super Efficient Baby Care your baby before he's taken away. Right. Back to upgrading your shower and toilet and fridge!
My villainous Sim who's there to pick a fight so he can have a Declared Enemy for his Public Enemy Aspiration: Uh, hang on, before we fight I need to feed your baby and change his diaper, the popup says he's going to be taken away. Right. Now that the baby's taken care of, LET'S FIGHT!!!!
My Black Widow, who's there to seduce her next victim: [BABY NAME] IS VERY HUNGRY, BE SURE AND FEED HER BEFORE SHE'S TAKEN AWAY... Uh, hang on, just a sec, before I do my spiel I need to feed your baby and change her diaper... okay, back...
(IOW, my Sims, no matter who they are or why they're there, do not ignore crying hungry babies if I'm controlling them. The Watcher spoke to them and told them to FEED THAT BABY. The Watcher has also been known to use bb.enablefreebuild to give bedless NPC toddlers a place to sleep and a potty and some toys. That said, yes, uncontrolled Sims just stand in the room with their starving, crying baby chatting about the weather and completely ignoring him/her.)
(Edited to add: And yet, when you're playing at a household with YOUR OWN baby, you can't get to your own crying baby due to the herd of NPCs rushing to wring their hands uselessly over the crib... Or, as I said at the time, "Mortimer, I love you dearly, but if you don't get out of the way so we can tend to that baby I'm going to have her vampire Mom BITE YOU.")
