EndNote on High Sierra : a nightmare !

I have been using Endnote X8 on High Sierra for a year or so.

My library has 2500 references, most with annotated PDFs.  Endnote has been slow from the begining, taking ages to open or crashing half way through. However, since last week I cannot open my library AT ALL. The program crashes when I try opening it, or tells me that the program is being used by another user (which is not true).

I’ve been in contact with a very nice Clarivate advisor who’s matter of fact defeatist reply was " We have identified that the libraries that have PDFs with extensive annotations are hanging in the Mac OS which causes EndNote to crash".  That’s it, deal with it

I’m moving to Zotero, but since I cannot open my Endnote library, I cannot export it into XML format (the format needed by Zotero). Does anybody have any tips as to how to go about this?   Thanks in advance!

PS:  It beggars belief that EndNote is still selling its faulty product to Mac users without warning them of these issues (and pretending it’s an Apple issue).