This issue has been there since the start of the game, so maybe a bug report exists somewhere already.
For multiple wall patters that have this vertical edge part, it is not applied correctly on corners when the wall is only 1 piece wide. I would expect it on all outer corners.
As you can see on my house here, it does work as intended on the first floor but not on the bottom floor on either side of the door.
From the other angle one white piece is applied on an inner corner but only on the right side, not the left side
here is another example
It would be nice if it could work similarly to floor tiles where the alt key can place the corner item. Most of the time we get a swatch without them too. Even with floor patterns cutting it up fixes 90% of design issues.
