@Caleb666 - I will take a look later into that, thx again for reporting it.
@tweebee - when you do a download via the right-click, you are leaving it up to Calibre to decide which version of the book results to pick from, in the situation where multiple results come back and it decides that they are not in the same ISBN pool. In that circumstance, it could well be that the decision Calibre makes means that it picks results from other metatadata sources, and discards the B&N result (hence why you see no B&N id). The same thing would happen if you use the Edit Metadata dialog in that particular circumstance, except you are probably manually picking the B&N result in the situation where there are multiple to match.
So in direct answer to your question - if Calibre picks the metadata result which came from B&N, you will see the B&N id immediately appear in the book details panel.
You can usually fix this by doing a second metadata fetch, as the first metadata fetch would most likely have changed the ISBN associated with the book, which *might* result in getting a different match from B&N that is in the same ISBN pool (set of ISBNs identified as representing the same book). However it is usually best to do this via the edit metadata dialog, or else if again there are multiple results it will be left to Calibre to once again decide for itself and you may end up with nothing changed.