Walls disappearing in cross section

[KeesW]

Several walls, shown on my floor plans, are disappearing when I generate a section. I can drag the missing wall in my section and it appears to the side of my cross section. It only happens in 2 of about 10 cross-sections on the project I am working on.

Alongside the missing wall is site mesh which had been cut using SEO. Could this be affecting the wall? Can I reverse the SEO to check what it was before?

[Anonymous]

Have you checked that you haven't inadvertently copied the affected walls over themselves? I've occasionally done so and have not picked it up in plan, but in section they seem to cancel out and appear missing.

[Barry Kelly]

And make sure you check in your hidden layers.
Even when the layer is off, if it has the same intersection priority number as the layer with your wall in then they will trim each other.
Barry.