Did you cancel the interaction then ask them both to play at the same time? All I had to do was ask them to play, it triggered before they actually started playing.
I canceled the interaction and then redirected my sim to play the multiplayer game with two other sims but it never registered. Strangely I saved and exited the game and later that evening when I returned to that sim it completed the objective as soon as I entered.
Glad it finally triggered for you. On top of delays, some of these triggers are odd at the least. But hey, if it works, we just ride with it...
😉
