Pdfs disappearing from Endnote8

I have a research assistant who says that when clicking away from a record in Endnote8 on Windows a recently attached pdf disappears. Attaching & disappearing pdf apparently happens randomly and multiple times before it finally “sticks.” The pdf disappears entirely from the endnote record but is still present on the harddrive (ie, Endnote is not displaying a broken link).

Has anyone else observed this behavior?

The pdfs are mapped to a location on the computer harddrive rather than stored with relative links within the Data folder. I am doing this because 1) I want to maintain a separate archive of pdfs and 2) because of their size including the pdfs in the Data folder rapidly makes for an impossibly large folder that is difficult to transfer from one computer to another.

I am stuck with ver8 because this is the last version in which I can actually search and replace the path name on file attachments, a functionality that was lost in subsequent version and one (of many) functions that I desperately wish were reintroduced in current and future editions.

Many thanks in advance for any assistance.