Unwanted Black Background & Underperforming AO in duplicate project

I’m duplicating a project by recreating it. (I’m deriving a metric template from an imperial one.) Copying elements over, adjusting text styles, etc. I’ve uploaded the two projects to dropbox and shared them with the Va team, but I don’t know that it’s a Va issue. I can upload them to the Rhino team also. Thanks.

Here’s the imperial one, displaying (and printing) correctly:

Below is the metric one I’m generating from copied elements. Some elements haven’t been adjusted yet and don’t yet match, but I am having trouble with the following: This project has a black mass or background in some viewports (and not in others, though the view modes are identical.) The Aerial Perspective only shows that black background when active, but ithas another problem also: It looks shaded though it is set to an Ambient Occlusion View Mode. These problems print as well.

The AO anomaly is likely a Rhino issue. Comments encouraged.

(The black is from a text scaling issue with Va-generated documentation objects copied from projects.)

Update: I have copied the layout and in one version zoomed around in the problem viewport and when I approximated the original viewpoint, AO was operating again. Now I have two copies of the viewport, with AO operating properly in one and not in the other. The only difference between them is that I zoomed around differently in one than in the other.

Another Update: It turns out that I can make AO come back reliably after it has disappeared with zoom > drag window. No other form of zoom (or anything else I’ve tried) will restore it. So that’s a work around, but there’s something wrong somewhere. Update 6.8 didn’t fix this issue.