Just in case someone else is having issues, I eventually got it in a two player (both humans) game when player 1 sold their house before the end of the game (also, in a previous game, the same thing happened to player 2 but it didn't trigger).

Recap: it seem like you have to sell your house before reaching the end of the board (selling your house at the end doesn't seem to count); and it also it seem that it must happen to player 1 for it to count

Thanks, I was wondering why I haven't been able to get it.

me to