File type image or file not upload

I use a field to upload a file (type = file or image) within a group.

N.b. I also use extension for custom table

But the file is not uploaded what can I do?

$meta_boxes[] = array(
    'title' => 'PORTFOLIO',
    'post_types' => ['page'],
    'storage_type' => 'custom_table',
    'table'        => 'IMAZ_agenzie',

'fields' => array(
                     array(
            'id' => "portfolio",
            'type'   => 'group',
                'clone'  => true,
            'sort_clone'=>true,

        'fields' => array(
                  array(
                    'id'   => "img",
                    'type' => 'image',
                    'max_file_uploads' => 1,
                    'force_delete'     => true,  
                    'name' => 'Immagine',    ),

                   ),
    ),
            ), 

);