Problem with additional custom field in existing meta box

Hello,

I hope you will be able to help me on this. I created for my project a few meta boxes with a number of custom fields a few month ago. Today I wanted to extend one of them with addition custom field (url link). I added it to the code as I did it before but nothing has been displayed unfortunately. It looks like the new field is not "accepted". I am enclosing the code for your attention below.

I will appropriate any help on this matter.
Thanks!

<?php
// meta box for Homepage  - Benefits Section
$meta_boxes[] = [
        'title'  => esc_html__( 'Benefits Section', 'lhk' ),
        'post_types' =>   [
         'page',
        ],
        'context' => 'after_title',
        'priority' => 'default',
        'autosave' => false,
        'include' =>   [
          'relation' => 'AND',
          'template' =>     [
              'templates/template-homepage.php',
          ],

        ],
        'fields' => [
            [
              'id' => 'benefits_h1',
              'type' => 'text',
              'name' => esc_html__('Heading Text', 'lhk'),
              'desc' => esc_html__('Please insert your text in the box.','lhk'),
              'size' => 85,
            ],
            [
              'id' => 'benefits_text',
              'type' => 'textarea',
              'name' => esc_html__('Description', 'lhk'),
              'desc' => esc_html__('Please insert your text in the box.','lhk'),
            ],
            //***** This is a new custom field I wanted to add
            [
                'id' => 'benefits_button_heading',
                'type' => 'text',
                'name' => esc_html__('See more Features', 'lhk'),
                'size' => 85,
            ],
            [
                'id' => 'benefits_button_url',
                'type' => 'url',
                'name' => esc_html__('Redirection URL', 'lhk'),
                'desc' => esc_html__('Please insert URL address in the box','lhk'),
                'size' => 85,
            ],
            //*****
            [
                'id'     => 'group_benefits',
                'type'   => 'group',
                'clone'  => true,
                'sort_clone' => true,
                'collapsible' => true,
                'add_button'  => esc_html__( 'Add FlipBox', 'lhk' ),
                'group_title' => esc_html__( 'Flip Box', 'lhk' ), // ID of the subfield
                'save_state' => true,
                'fields' => [
                    [
                        'id' => 'benefits_image',
                        'type' => 'single_image',
                        'name' => esc_html__('Icon/Image', 'lhk'),
                        'desc' => esc_html__('Please upload your image.','lhk'),
                    ],
                    [
                        'id' => 'benefits_front',
                        'type' => 'text',
                        'name' => esc_html__('Flipbox - Front', 'lhk'),
                        'desc' => esc_html__('Please insert your text in the box.','lhk'),
                        'size' => 85,
                    ],
                    [
                        'id' => 'benefits_back',
                        'type' => 'text',
                        'name' => esc_html__('Flipbox - Back', 'lhk'),
                        'desc' => esc_html__('Please insert your text in the box.','lhk'),
                        'size' => 85,
                    ],
                ],
            ],
        ],
    ];