Column order matters. (Some.)Whether uploading new content or revising existing metadata, the Title field must always be present, and must be the very first column of the spreadsheet. When revising, the 4 gray "system fields" (calc_url, context_key, issue, ctmtime) must be present and must be the last 4 columns in the spreadsheet. Any other columns can be moved around between those, or deleted if they're not needed.