Is it possible that your endnote preferences are looking for a tempory delimiter that is different than the default curly bracket? You can check in the edit bibliography menu (just for that manuscript) or Endnote preferences (for all manuscripts) settings. Both are shown in images attached.
Yes, I note you say you were trying to “edit citations” but first you need to format them – “update citations and bibliography” but if you are getting that com exception, you need to figure that out first.
For the record, the citations don’t neccesarily haveto be formatted to be edited. They just have to be formatted to use the built-in Edit Citations tool. As such, if you would like to add pages to your citation you would add “@[page]” at the end of the unformatted citation, e.g. {Rohde, 1998 #485@4-5}; if you would like to add a prefix to your citation you would add “[prefix]” at the beginning, e.g. {test\Rohde, 1998 #485}; and so on depending on what it is you would like to edit with the citation.
However, this just let’s you edit a citation that is unformatted and you would later have to format your citations if you would like to have the citations automatically appear in your bibliography for example. The manual edits would then “transfer” to the now formatted citations. This method could be used to faster edit your citations if the bibliography of the document is quite extensive and it takes a considerable amount of time for the citations to be formatted.
This may or may not be an answer to your question, depending on what it is you would like to edit with the citation and to what purpose.