Yes I even tried drawing my own wall, select it but even this wall did not show in the 3D view. Further more I did a new file with current settings, so using the clients file setting. Even in the empty file if I draw a wall it will not show up in 3D view, which is extremely strange and I have not seen this before, using ARCHICAD for now almost 30 years. I like to add on, when I try to draw a marquee tool in the 3D window or I draw a rectangle with the arrow tool, you usually get visual feedback of the frame you about to draw. Not in this 3D view, the frames don't show either while being drawn.
Interesting in regards to the large SEO, that is a possibility but as mentioned above in the new file it still is not working. It looks like when I click on the roads on the terrain they have used a SEO. Will check this out never then less tomorrow first thing, I might get lucky!
BTW the 3D Studio Max render looks fine, so apart from not seeing the 3D model it sure is there .
AC 3 to 26 -Windows 7 - 24GB - 8core 4.4Ghz