Invisible Lines from which Walls were made

Most of the curves from which walls were made in this project are invisible, though selectable. Curvesw from which Rhino objects were extruded are visible. The invisible curves don’t show if the walls are deleted, nor if the raster image at the same elevation is moved or deleted. They show if they are moved or copied, however, including Copy Inplace.
InvisibleLines.3dm (8.9 MB)

Once saved and reopened, this issue isn’t repeatable, but it was there for about an hour until I saved the project with a different name (including the one I just uploaded.)

This is what I see when I open this file:

The right side of the image shows a Plan view with missing lines. After updating it, all lines are visible, except an open mesh that is not shown in the plan view:

If you run into the same problem again, please let me know how to reproduce it.

Yes, they were missing from the Plan View on purpose, but only save/close/reopen brought them back in the model. It’s an easy fix, but something to be on the watch for.