update_post_meta for cloneable fields in a group.

Hi,

I'm trying to get this to work but for some reason its not. Here's my fields

$meta_boxes[] = [
        'title'      => __( 'Order Details', 'your-text-domain' ),
        'id'         => 186,
        'post_types' => ['fr_order'],
        'style'      => 'seamless',
        'fields'     => [
            [
                'name'   => __( 'Guest Names', 'your-text-domain' ),
                'id'     => $prefix . 'fr_guest_names',
                'type'   => 'group',
                'fields' => [
                    [
                        'name'  => __( 'Guest Name', 'your-text-domain' ),
                        'id'    => $prefix . 'fr_guest_name',
                        'type'  => 'text',
                        'clone' => true,
                    ],
                ],
            ],
        ];

and here's my code for updating:

$post_meta = Array
(
    [0] => Array
        (
            [fr_guest_name] => Amet tempor nisi
        )

    [1] => Array
        (
            [fr_guest_name] => Condimentum a
        )

    [2] => Array
        (
            [fr_guest_name] => Mollis sed posue
        )

    [3] => Array
        (
            [fr_guest_name] => Arcu a eget euis
        )
)

update_post_meta($order_id, 'fr_guest_names', $post_meta);

The post has already been created and the $order_id is the wp post id.

I get a meta ID returned from the update_post_meta function but the names don't show up in the admin area:

https://www.dropbox.com/s/luoigwe59tqzq3x/metaboxclonablegroup.JPG?dl=0

Can you help?