I've done a search and can't find anything relating to this, so sorry if it's repeated.
In AC10 (first build, no hotfixes) Sections and Elevations are sometimes not drawing the whole model on a rebuild.
For example, in the image attached, you can see a giant white patch where the roof of the building is supposed to be. It's been there up until now, but sometimes after making an alteration and rebuilding the view, it goes away. Other times, it does what you can see in the second image - rebuilds most of the model but leaves a few bits out.
As far as I can work out, there is no pattern or particular reason this happens. Also, it only seems to happen to roofs in elevation and section, and windows in section.
To fix it, I have to move the section line a millimeter or 2, do a rebuild, and hopefully it fixes. But sometimes it doesn't. hmmm.