i found out it is due to ambiguous citation. If i change the Name format in the ‘‘Include the authors initials or full name in citations’’ menu in ‘Citations’ → ‘Ambiguous Citations’ and update my bibliography the citation changes, e.g. to ‘(JW Ross & Feeny, 1999)’ or whatever i choose.
However , if i remove the checkbox for ‘Include the authors initials or full name in citations’ and update my bibliography the initals are still there. Why???
Check the Author field for the records listing J. W. Ross as the first author. There is likely some variation occurring in the name (e.g., extra space) causing Endnote to treat the reference as written by a different author. If you’re unable to identify the variation then just copy the author name from the correctly cited reference record into the Author field of the problematic record.