[OPEN] Parents refuse to care for toddler

I am also experiencing this issue, now specifically after installing the 5 year anniversary update, and Realm of Magic. (PC) I am not sure which pack/update is causing it as I did not have time to play between the two releases.

I am currently on the 3rd generation of this family when it started:
- Two sims (I'll say "A", top level celebrity, and now a spellcaster, and "B", normal sim) adopted a baby, "C", and raised the baby no problem. No issues during baby or toddler stage. That C sim is now an adult. (Regular sim, one star celebrity.)
- Installed the 5-year anniversary update, and Realm of Magic.
- C sim got married to "D" (vampire), and had a baby, "E" (also a vampire).
- A and B generally ignore baby E. The parents, C and D, simply will not do anything I ask them to in regards to caring for E. Interactions will queue, but they just don't run. If they do run, my sims do other random nonsense. If I leave them to run autonomously, C and D just fight over E in that all they do is take turns picking up E and putting her back down.

A couple of examples I remember: Parent C and toddler E were upstairs in a room with a high chair. I told C to feed E. She picked up E, takes her downstairs for some reason and puts her down, then picks up a bowl of food, takes it back upstairs and put its on the high chair, then comes back downstairs, picks up toddler E, and takes her outside. Interaction then drops from queue. 

Parents C and D decided they both needed to bathe toddler E at the same time. C carries E into the bathroom and puts her down. D then comes into the bathroom, picks up E, takes her a different bathroom to do the same thing. D puts her down and the interaction drops out of the queue. 

Another time, toddler E was sitting on the ground between the high chair and the potty. C comes in to feed her at the same time D tries to potty train her. They just take turns picking her up and setting her back down for several sim hours, accomplishing nothing.

Every time that her needs got low enough to need parental care, I ended up having to cheat her needs back to full because all of the adult sims are simply running amok.