Ticking the box for "Disable Caregiver Autonomy for Infants" makes the infant glitch out so they can't sleep.
The infant is put to bed. It gets a "Sleep" activity prompt but lies awake and still while needs are still getting lower.
Un-ticking the box for "Disable Caregiver Autonomy for Infants" solved the problem and infant went to sleep immediately.
Bug to fix: Making sure infant activities work as intended even when the box for "Disable Caregiver Autonomy for Infants" is ticked.