A picture = 1,000 words.

Can you post an image of the logo/and or your traced AI image?

You might have selected the Outline option in Xara 3D. I don't have Xara 3D Maker installed at the moment but as I remember the is an icon with an O that is outlined. And I think it is in the Extrusion tab. If that is selected, un-select it and see if you have a solid shape.