I have the same exact issue, and posted what happened on another post, but I wanted to ask: How do we check to see if our antivirus is flagging the game?
So what happened: I made a Sim family twice, with an adult and teenager. The first time, I reloaded into the game and the adult vanished without a trace and I had not looked into anything else in that family. The second time, same family, I reloaded into the game and the teenager vanished, but the adult had memories with the teenager still with "$Subject," to replace the name. Both time on the loading screen they were both there, but when you click on the family, there is only one sim.
It's just so frustrating😫 and hopefully the sims team fixes this asap, it seems to be happening to everyone, I see it on the steam community too. For now I guess time for the single life for my sim...