Shrubs showing as 3d boxes

[simon829936]

I am having a small problem with placing of shrubs. Trees seem to be alright but when I place RPC shrubs in a view they seem to appear correctly in plan views but in 3d and elevation views they only show up as 3d cubes, just wondering if anyone else is having the same problem and if so, is there a simple way of rectifying it?

Thanks

Simon