So I found a fix for this issue in Endnote X9 on mac.
Convert to Unformatted Citations (Endnote bar, Tools, Convert to Unformatted Citations)
Note- my citations became {Author, year, number} {Author, year, number}
Find and replace “} {” to “}{” (delete all the spaces between citations).
(If you have any naturally-occurring (non-citation) “} {” brackets in your text, change these uniformly before this step.
Update Citations and Bibliography.
Note- I had to copy and paste plain text into a new word document before doing this final step, otherwise it would have me go through and manually identify many citations, then in the end didn’t do what I wanted. I am not sure why I had to copy and paste the text to a new doc, but it helped avoid this).
Hope this helps for those encountering this issue over a decade after it was originally fixed.