July 2018 - last edited July 2018
I know, so stupid, it bugs me so much. My guess City Life penthouses or apartments being added has made this bug and their unable to fix without redoing the whole system. My guess is they'll won't fix it due to amount of work it will take.
As you can see in the right side of the brown house there is a section on the top floor where the trim is not, that is where the stairs are. This lot was built with no mods or cc in game (I don't even have any) and in the beginning with only maybe outdoor retreat ep and whatever came before that. In other words it was a very early build. It seems to me that it has to do with the way the trims work on rooms. Maybe that it recognizes that the stairs are a room, but that room is not able to have trim on it. (Just a thought.) Also, this world is New Crest, but this happens everywhere. Thanks for reading my comment.
I noticed this the first time I put exterior trim on a house, and just thought it was supposed to do that when I kept getting the Nothing to Change message. Then I saw this thread and realized it was a bug. I'd like to see it fixed too, I can't always just cover the spot with a tree or something.
I also have this issue! Only thing that works is using a frieze instead of trim, which works in some designs, but doesnt work for all!
This drives me crazy but I just found a workaround that has worked for me!!!!
I place the stairs one block away from the wall and then using the arrows stretch it to touch the wall (making it double wide) and then I can even make it one block wide again and it works!
I hope this works for others!!