I recommend contacting Tech support but they will want to know: what Operating system and what version of endnote?
Have you ensured you have updated/upgraded endnote to the most recent version? (X8.2)
If that does not help then:
I recommend that you contact Technical Support directly
1-800-336-4474 option 4 then 1 or
https://support.clarivate.com/Endnote/s/technicalsupport?language=en_US