Hey! This isn't enough information for me to know, but it sounds like there are three cases here.
If you loaded the game and Sim view of other Sims changed, has their preferences changed as well?
- If they didn't change, but the view of other Sims did, then something about these other Sims changed. When their outfit or body changes, the view changes as well. This will especially happen when you edit them or remove CC clothing. Additionally, if you have the "Attractiveness Dynamic World View" enabled, Sims views will change with how the world changes and you might have very little control over it as that's how fashion and cultural/social preferences change.
- If they changed to something seemingly random, did you ever set their preferences in CAS? These preferences will override any other preferences you set or develop later in the game. If you didn't, I'm not aware of a situation where this can happen as Sims with already set/developed/randomized preferences are blocked from having new preferences therefore making it impossible to happen.
- If they changed to nothing, meaning they have no preferences selected at all, that sounds like you lost your WW save data. I'm not aware of anything that can cause this to happen. WW save data is embedded in the game save itself, using a fake empty household that holds global information about all Sims and the world. If for some reason that data goes missing or cannot be loaded, then that would result in preference missing as well. The issue is, I don't know of anything that would cause this data to disappear or fail to load. Thus far nobody is able to explain to me how and when it happens so I'm unable to help.