How to find the offending ambiguous name?
I have three references with the same author, First M. Last (all are multi-author works; as it happens, Last is first author in each). Zotero APA6 insists on disambiguating this name (Last, First M.). I've searched everything I can think of, and I can't find any other authors named Last. I suppose that a translator or editor, etc., named Last would trigger this, but I have found no field anywhere that contains the name Last. I tried making all three First M. Last, then Last, First M.; this changed nothing. Any suggestions?
Zotero would disambiguate as "First M. Last" in APA, not "Last, First M." If you're actually seeing the latter, it would seem like you have the name entered incorrectly (maybe the whole thing including comma in single field mode?)