Hi I have also noticed this with cupid corner sims! For me it has been other user gallery created sims from Cupids Corner. I have no mods/cc and latest update. Version 1.116.232.1030 DX11 Laptop Mode
The bug seems to be happening when editing the sim also with testingcheats on and cas.fulleditmode The sim will revert to the outfit and looks of how they first met. Examples of when it happens Ive noticed are : When traveling to another lot ie a date, taking a photo with... Sometimes when returning to lot they are also old persona. When going in to edit with cas.fulledit mode they are the new edited version and when you save and go back into live mode they are still old persona. 50 First Dates playthroughs can work well with this bug hehe
