When attempting to upload users via CSV file, if "Preview rows" is set to ten, for example, then the presence of duplicate or pre-existing field values, e.g. email address, in the first ten rows of the CSV file seems to cause the "Settings", "Default values" and "User List" sections to disappear at the next page, preventing the upload. The presence of these duplicate field values can be seen by scrolling to the right of the "Upload users preview" at this page.