Whatever,
You are not alone... This has been happening since SEO's came out...
There are occasions when elements, such as windows, will CAST a slab to infinity while viewing in a 3d window (with marquee from floor plan)...
My work around is to view ALL instead... I know, not a fix... just a way to get it done..
I have no idea what the impact in in the 3d Document window...
Duane
Visual Frontiers
AC25 :|: AC26 :|: AC27
:|: Enscape3.4:|:TwinMotion
DellXPS 4.7ghz i7:|: 8gb GPU 1070ti / Alienware M18 Laptop