It is working like this in my game and I thought it was working as intended that is why I would like you to verify. My Sims that are on community lots playing chess or fishing do gain skills when I am playing another household. If they prevent played Sims from gaining skills when they are NPCs but they still do, it is an issue.
Yes, mine do too but there's nothing I can do if I don't get an answer.
Sims also gain romantic relationships when you're not playing them and that can be explained in a similar way (flirty Sims on community lots). I do believe that's how it works as I don't believe they actively prevent it. A modder might know more though.
I don't know if it has always been that way or if it got changed along the way.
If you have a twitter account, you can try asking them yourself. I do have channels to forward stuff but those are mostly one way streets. I get most answers through twitter myself.
