Ideas
Today I had the mother Sim queue up a numerous actions, but she continuously adds "check infant" or "put down" infant Sim (infant is always already on the floor or in a crib) randomly. Even if I cancel the action in her queue, she walks all the way to the infant before cancelling the action. In one instance another Sim on the lot was actively having tummy time with the infant when the mother Sim tried to interrupt to "put down" the infant Sim. In another instance, the mother Sim successfully put the infant in the crib and went downstairs to autonomously crochet. I cancelled that and told her to knit, selected an object... and then my Sim went back upstairs to "put down" the infant Sim she just put to sleep. Frustrated, I shift-clicked and reset the mother Sim and then she went back downstairs to knit. Before even making it down the stairs she autonomously queued up "check infant" which I cancelled. The infant's only low need is sleep and they are in their crib.
The other adult Sim in the household is not related to the infant and never autonomously checks on nor puts down the infant Sim.