Truncated PDF File Name

I have been an EndNote user over many versions and have amassed a large library of references and associated PDFs. Over the years, I have taken the time to create useful names for my PDFs that include authors, date and abbreviated title and abbreviated journal name.  I could drag and drop them onto the references in my EndNote library and the file name was retained.  I have a naming convention that I like and with a library of several thousand publications, don’t want to change.

Then I upgraded to EndNote X7.

I like some aspects of the new interface but I do not like the way that the PDF subfolders are now meaningless numbers rather than names related to the PDF.  I can get used to that I guess but what I really, really don’t like is that I have just discovered that the PDF names that I take the trouble to create are truncated when I import (usually drag & drop) the PDFs into EndNote, despite the fact that the PDF preferences are set to “Don’t Rename”.  All the PDF names that existed in my library when I upgraded to X7 still have the names I created so there is no restriction to file name length.  Am I doing something wrong? Can I stop them being truncated?  I realise there is an automatic naming function but that will not generate the abbreviated formats that I like to use.

Grateful for any suggestions to fix or work around this issue.