cas.fulleditmode won't let me modify relationships in CAS

Hello! 

In the past, I have been able to use cas.fulleditmode to edit the relationships of townies in CAS. Today, I went to do this, and it said I could not edit pre-existing townies. I was not getting this message in any other place in CAS, such as sexuality or gender identity. It was just there. I used to use the cheat to make different Sims spouses since the game does not automatically non-played Sims together, but it didn't work today even after restarting the game as well as trying it in both manage worlds and live mode. If this change was done on purpose, it is definitely an inconvenient one. 😅

I don't use mods or CC.