Because your wall is a "wall" and your roof is really a "wall" as well then you will need to look at the Priority strength for each wall.
This will affect which wall will cut any other wall.
In your case the wall is stronger than the roof so it is trimming a hole in the roof and therefore there is nothing to use as an SEO.
Select the roof in 3D and you will see the hole highlight.
Change the priorities so the roof is stringer than the wall..
Just to make things more of a challenge you could also place them in separate layers and if these layers have different intersection priority numbers then they will not trim each other and SEO will work as expected.
Barry.
One of the forum moderators.
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