Packaged library behaviour on a Mac?

I’ve just encountered a user who managed to save his library in .enp format.

This was on a mac and I only have a windows machine for testing, so I can’t reproduce exactly what he was doing, although I succeeded in saving a copy of the library in .enl format with its accompanying .Data folder. 

The main symptom that was causing him difficulties (and made him come to our help-desk for advice) was that he could no longer attach new PDFs to records - presumably because .Data no longer existed in its normal state - and that PDFs he’d previously attached to other records no longer opened when clicked.

Once I retrieved the .enl and .Data pair he could add new PDFs once more, but still couldn’t access the ones he’d attached before creating the package library.

Is this normal behaviour?

He’d also done some odd things in his attempts to retrieve the situation, like saving copies of his library INSIDE the .DATA folders of earlier versions of the library, which I guess would tend to confuse EndNote and I’ve advised him strongly that there is nothing inside .DATA that humans can safely tinker with directly.

However I’d appreciate any suggestions on whether there’s something more useful I could have done to retrieve the situation.