You can try the steps for the error Cannot Edit Range on our wesbite:
https://support.clarivate.com/Endnote/s/article/EndNote-Cannot-edit-Range?language=en_US
If this does not help I would suggest contacting Technical Support:
Please contact Technical Support directly
1-800-336-4474 option 4 then 1
or
https://support.clarivate.com/Endnote/s/technicalsupport?language=en_US