Hi and welcome to the Forum!
I do know there have been cases of sims being "reset" if the game is saved and exited while they are at work, I don't recall a fix for it, so maybe just try to save and exit either just before or just after they return from work! You can also try the usual fixes of clearing cache files, repairing the game via Origin, or doing a factory reset. There are some really good threads on the boards about how to do these things. Also, if you use mods or CC, try playing without them and see whether that helps. I personally have no mods or CC and do not have this issue (although, I do have some other career related ones, unfortunately)
At this point it seems as if bugs tend to be random. Some people get them and others (with identical setups) don't... I'm sorry that you are one of those who has this particular bug :-( it can be a nuisance!
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