[RL] All babies are being born 'secret'

My Sim had a baby with her fiancé and in the family tree, the baby is listed as a “secret child”, even though no one cheated, they are only partners with each other, and there was no other possible father at any point.

Having the baby didn’t check off the fiancé’s “Have a child” wish in his Soul’s Journey, as if he didn’t know the child was his, even though the mother shared the news with him after taking the pregnancy test, and he did the “Pre-parental panic” action while she was in labour. I’m not seeing any way to edit the relationship in the family tree, or any kind of interaction between the parents that would reveal the existence of the child, either before or after its birth.

I also tried having them elope before the baby’s birth, in case the issue was having a baby out of wedlock, and that didn't fix. Then, I tried using cas.fulleditmode to make the baby his son, and that checked off the wish in his Soul’s Journey, but the family tree still says the baby is a “secret baby”. 

The only explanation I can think of is that the baby was conceived out of wedlock, but it seems silly for that to automatically cause the baby to be a secret when the parents are romantic partners and neither is cheating on the other. That being said, the secret baby isn't showing up in the secret/scandal section of her notebook, so I think it may just be an issue with the family tree? I ended up quitting without saving and am not touching that save for now.

For info, I have all the expansion packs, game packs and stuff packs, but don't have most of the kits. I don't use any mods or CC, and play on Mac.