Yes I’ve got it working! For anyone that’s interested I replaced the $filename with $filepath in the following 2 lines near the end of front-end-upload.php:
header ( ‘Last-Modified: ‘ . gmdate ( ‘D, d M Y H:i:s’, filemtime ( $filepath ) ).’ GMT’ ));
header ( ‘Content-Disposition: attachment; filename=”‘ . basename ( $filepath ) . ‘”‘ );
