Sorry, I've re-tested again in light of my new foundings. I didn't realize there are buyable bassinet in buy mode (my sim started to give birth after GTW released so I always give birth in the clinic)
I would guess you have 'bb.showhiddenobjects' on, if so, you would be able to search for two kinds of bassinets (but with the same name, 'Rock-a-bye Bassinet') both kinds looks identical and cost 150, but the one in the cheat catogory will auto-spawn babies in it. If you use the search function, it may lead you to the wrong one, that might be your issue here.
Be sure to always buy bassinets from: Buymode (objects by function)/Kids/Kids furniture, that way you won't get the wrong one.
Hope this helps. Happy simming!
