So to try to answer your questions, but I only know from what I have tested so far:
When reloading into the game, my sims preferences towards other sims were completely wiped, it showed no preferences in the menu, but they would still find some sims attractive/extremely unattractive etc. I set their preferences up and it seems that it fixes everything, they begin to find people I had selected attractive/very attractive etc.
Then save and quit, reload the game, all the preferences are lost again.
I thought maybe this could be a conflict with another mod so I tried without any other mods, same occurrence.
I tried in another save to see if my save was broken. The same thing happened, sims don't have any auto generated preferences, so I developed their preferences, they found their SO extremely attractive, save and exit. They have lost their attractiveness settings again.
None of these sims have their preferences set up in CAS as I know they overwrite the menu ones, so I made sure to check that.
But from what I know, I had my subscribers on YouTube check and they're also having the same issue of sims having no preferences set up and changing them doesn't save.
For me, this only started occurring as of the newest patch as everything was fine before that for myself.
Hopefully some of this info helped with solving what the error is :)
I have the exact same problem, I tried setting preferences and playing the game on different computer, with and without other mods, and the preferences are ALWAYS wiped when I restart the game like for MissLollypop! It happens with all sims not only the played ones and not only on adults sims, on teens and young adults too :)
I tried just launching the game, setting the preferences, and then immediatly close it and re-launch to see if it would be wiped even if I don't play with the preferences I have set. It wiped it even if I didn't play !