Since the new update, I've checked in with all of my sim homes with infants (3) and all of them who were in bed, sleeping, were found sitting up, awake. This happens all the time with the toddler sims, but as soon as you unpause the game, the toddlers lie back down and fall asleep immediately. However, I had to tell the infants to 'try to go night night.'
Also, I purchased the new infant play mat for all 3 households and now the infants will not fall asleep in their cribs when they're put down - fed with clean diapers, energy down to about half, etc., all ready for bed. I'm having to tell them to 'try to go night night' even though the 'action' says they are trying. I get a warning about putting the infant down for a nap, but they have been, they're just not falling asleep like they used to. They do usually have a cry, and the parent soothes them, but this is different. They are in 'happy' mode and are just not falling asleep.
Edit By crinrict: Adjusted Title to better reflect the issue