@crinrict OK, I've tried a few more things:
1. I moved a duo into the same tiny home, and neither of them got the effect
2. I moved the original problem family back into the home, and this time NONE of them got the effect. And yes, I did check three times to make sure the lot settings were correct.
3. I tried the original foursome in a newly built micro home. None of them got the effect.
4. I tried a new threesome in a micro home downloaded from the gallery. Back to the beginning: 2 got the effect, and one did not.
This is driving me nuts!
