[GRO] Infant/Toddler wont achieve milestones

My infant achieved "sit up" three times in a row and was unable to unlock this milestone thus I was unable to progress to the highchair.  I love the milestones (and infants, for me the best lifestage in the game) and I don't want these bugging out.  Though the biggest annoyance was dad waking up from sleeping (as he was sleeping in the same room as mum was practicing sitting with infant - yay to tiny home living) to watch the milestone for sit up.  We'd done this three times already - it's not unlocking for some reason - go back to bed already, you've taken the photo three times and it's not unlocked.  Though the game kept implying sit up had been achieved, as I had the purple pop up on the side panel, the infant is visibly sitting for a second, the milestone was not received by the infant and the game said the infant needed to learn to sit up before using the highchair. 

I want to feed the infant baby food but I can't because sit up has not been achieved, however I visibly can see the infant sitting!  I put the infant to bed and apparently the infant can get it in the crib - never knew that, however though I got the notification of sit up being achieved (4th time now), and the infant was sitting in the crib, the milestone did not unlock nor did the high chair interactions.  Once the infant was removed from the crib it went back to not being able to sit.