In reference to what solitaire did to "fix" the problem, is how I severely corrupted my Property Data folder. I "assumed" (a long time ago) I could duplicate a PO and redo a few data base links. I would take a (example) 2x4 wall, copy it, and change the data base item from 2x4 to 2x6. All else stayed the same, so why bother to reconstruct the whole PO. Well, eventually it all blew up and I literally had to start over and rebuild over 75 PO's and links. So, I would not recommend copy/pasting from the file structure. It is ridiculous how tedious it is to make these things.
There has got to be a better way, more intuitive and safer. I would love to see a connection directly with composites (and objects), to link each skin directly in the Composite panel to the data base and generate a linked PO automatically. However, after a decade of wishing for improvements here, I'm not very optimistic it is in the cards.