The fact that the (1967) is not indicated in grey as a field, when the cursor is in it, does suggest that the Endnote fields have been removed.
Make a copy, and choose "Convert Citations and Bibliography> convert to unformated citations. Any that don’t convert to
{author, 2007 #187@@author-year} or {author, 2007 #187} will need to be reinserted.
(do the following on copies obviously) another possibility is to go back to a backup with endnote fields still in it, and do the Convert steps above there too and compare the two documents. Accept all the tracked changes in both documents and then compare the two using word – accept your recent changes, and reject any citations not in curly brackets. Then any remaining citations that are not in curly brackets will need to be reinserted.
If this document was opened in another program like OpenOffice that would erase endnote fields, or if you use the drop down option of “convert to plain text”. I try to always share with colleagues in the unformated state. Or check immediately when I get it back, so the compare option above is not too cumbersome, if I need to rescue the endnote fields.
I know - water under the bridge.