Is Panya Li flagged?

@MadameNordica I don't think any Sims have a specific flag on them to stop pregnancy. As long as you've edited them in CAS to make it possible it should work but what I'd do is move them into your household, or play them as a household and buy them the Fertile Reward Trait. Then keep trying. If that doesn't make a difference then something isn't working properly and I'd recreate a copy of the Sim if it was me. I know that's a bit immersion breaking but I've had to do that before when I've had a problem with a particular townie's characteristics.

Edit: some time later and just to update he does turn out to be a special NPC and it's reported that he can only be added to the household by using the MCCC mod. But that isn't possible for console players. Other players are raising this issue with this Sim too.