Have you tried exporting the prop with all the normals forward boxes checked on re-import? Have you checked the box in the advanced tab in the Material Room for "Normals Forward"?
If all that works, then save it to the Props Library, and name it what you like, and save it in the scene and stupid ol' Poser won't ask for goofy tags again with that.

I've done that HUNDREDS of times It works with hammering the normals forward.

I cannot save the world. Only my little piece of it. If we all act together, we can save the world.--Nelson Mandela
An  inconsistent hobgoblin is the fool of little minds
Taking "Just do it" to a whole new level!