Thank you for sharing the feedback.
My case is different. I’ve got a Word document populated with Zotero fields and the whole library in RIS. I successfully imported RIS to EndNote and want to convert Zotero fields to EndNote fields.
Technical support suggested converting Zotero fields to plain text and then issue the Update Citations and Bibliography command of the EndNote Word Add-in. It works fine but takes a lot of time and effort if I have several hundreds of citations.