[GRO] Infant looses Milestones after switching families

This is the second time I have seen this happen.  I have a sim who's infant is maxed on milestones or very close and when I come back to the game the infant is back to square one but only has a few days left before aging up!!!!

My current game had a Sim, her infant daughter and a child.  The infant has 7 days left til aging up to toddler and she had all milestones including clapping,  waving, pincer grasp, blowing kisses, crawilng, pull to stand - the firsts: blowouts, baths, visitors, foods, finger foods etc.  I saved the game a few days ago and when I opened it to play, the infant has ONE milestone- being born!  With 7 days til she is a toddler!    This is a game breaker for me. Spending hours playing and then losing all the things you gained while doing so!!!  AND this game was a scenario (the make a million one)

Product: Sims 4

Platform: PC

Which language are you playing the game in? English

How often does the bug occur? Twice so far

What is your current game version number? 1.98 .158 .1020

What expansions, game packs, and stuff packs do you have installed? Everything except vampires and werewolves and a few clothing kits

Steps: How can we find the bug ourselves? Play with a Sim and infant until the infant is close to aging up ( a week or so) then leave to another family for a few minutes. Return to first family play a bit and save. Come back later. infant loses all or most milestones

What do you expect to see? infant should have all milestones earned 

Have you installed any customization with the game, e.g. Custom Content or Mods? no mods or custom content

Did this issue appear after a specific patch or change you made to your system? Seems to have occurred in the last month or so

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