Trees:

[Quirk]

Placed the tree on plan, but in elevations and 3D views a large grey rectangle instead of a tree is shown. How does one place a tree on a plan and have it show up as a tree in the elevation and 3D views?

[Barry Kelly]

Sounds like you are using a 'billboard' style object.
These will show an image in 3D OpenGL and rendered images.
They won't show anything except the rectangle (billboard) in 3D Vectorial or elevations.

You either need an object you can place in elevation (with an elevation view option) - but this won't help in 3D at all.
Or you need a full 3D object which will look fine in any view.

Barry.