I think it's the same thing like with the Lightwave .lwo situation: .LWO objects will load if they were made with a version of LightWave 5.6 or earlier. The Lightwave people changed the format as of version 6.0. Vue will import .LWO files created no later than LW 5.6. I think that's the case for True Space as well: The ones which aren't importing are likely newer versions of the .COB format. Strangely enough, 3D Exploration can read all these files just fine, and it's current version is younger than Vue 4....