"Phantom" Ceiling Plane

[coogan]

I use F12 regularly (almost as often as I save, which is every minute or so). Makes no difference with this particular problem.

You'll have to explain the "overlapping roof planes; not properly drawn custom roof planes" thing. The now-deleted custom ceiling plane (I guess it's a type of custom roof plane), did have a "hole" in it, and I think the seam where I surrounded the "hole" (since you cannot make holes in custom ceiling planes) may have overlapped.

One more thing. I do remember seeing a warning message at some point about a roof, ceiling, or custom countertop polyline being open and needing a line or arc to make it a closed polyline. This particular warning happens quite regularly (with most plans I do) for reasons I can't fathom, since I never edit the segments of closed polylines separately. When all you do is move line segments, I'm not sure how it would be possible to cause a closed polyline to become open.

I will send the plan file as soon as possible. Thanks.