A Gedcom that uses UTF-8 encoding requires a tag saying it is a UTF-8 Gedcom. On importing the file, GedBox checks for that tag and correctly reports the file as a UTF-8 file, but then refuses to import the file if it lacks the additional signature header. FTM does not add a header, called a BOM, and the header is not part of the UTF-8 requirement - it is optional. GenBox's refusal to open it is an error, since Windows provides a function to check whether the file is UTF-8 or not. GenBox has a very nifty "Convergent Tree" which automatically selects multiple direct lines of descent that "converge". I found that I can add the header GenBox requires using an open source product call Notepad++. Open an exported Gedcom in Notepad++ and select the menu option "Encoding/Encode in UTF-8", then save the file. A byte is added to the beginning of the file that identifies its UTF-8 encoding. You can remove the header later by selecting "Encoding/Encode in UTF-8 without BOM", but that is not necessary.