Quote - When you say "no UV mapping", do you mean there are no "vt" lines in the OBJ?

Poser doesn't like models without "vt" lines.

No UV at all, no vt entries no uv indexes in face entries.
One more detail, as the models were huge in dimensions I first imported them in Poser, scalled down to something normal and exported again to be used in the scene, so the mesh was processed and exported by Poser first. I never tryied to render the original mesh.

THe sliced and glued mesh that works is the same as the original, the only thing that have changed is the vertices and face order, so the only possible explanation is that Poser is sensitive to the face or vertices order that appears in the file, it makes no sense, but is only sensible for rendering, importing, exporting, scalling, rotating, moving, grouping, spawning, works fine without any problem.

Stupidity also evolves!