John,
I would check if the issue could be version or platform specific.
If you are performing the steps on a MAC then try the same steps on Windows.
If you are using EndNote X9 then you could install a demo of a previous version from our website:
https://support.clarivate.com/Endnote/s/article/ka1390000008bfCAAQ/EndNote-Installer-download
I might also suggest contacting Technical Support they can help in doing these tests with a copy of your library.
Please contact Technical Support directly
1-800-336-4474 option 4 then 1 or
https://support.clarivate.com/Endnote/s/technicalsupport?language=en_US