I had a sim of mine come home from work and suddenly started doing the congratulatory action when he completed something over and over again. After I moved to another lot and came back to that lot everything was fine again.
Now and then this happens in my game, too. I also read from other players several times. Going to another lot and then back does help, but can be very inconvenient if a bunch of Sims come back from work or school at the same time. Most times my Sims rather plant beans instead of going to work, though.
Guess, this issue should be reported to Online Support.
