Meta box html is not updating after saving

snippet code of notification display when check notify checkbox and display message in Update and Publish post or page in admin

 function cabtv_add_post_options()
    {
        // Add our meta box for the "post" post type (default)    
        $post_types = array("post", "page");

        foreach ($post_types  as $post_type) {

            add_meta_box('cabtv_notif_on_post','Notifications','cabtv_notif_on_post_html_view',$post_type,'side','high');
        }

    }
    add_action('add_meta_boxes', 'cabtv_add_post_options');


    function cabtv_notif_on_post_html_view($post)
    {   
        wp_nonce_field( 'cabtv_notif_metabox', 'cabtv_notif_metabox' );

        $checked = get_post_meta( $post->ID, 'cabtv_notifications_sent', true);
        $check = $checked?'checked':'';

        if ($checked) { ?>
            <div style="padding:10px;">
                <span style="color:red; font-weight:bold;">Notifications have already been sent for this post.</span>
            </div>
        <?php } ?>

        <input type="hidden" name="cabtv_meta_box_present" value="true"></input>
        <input type="checkbox" name="cabtv_send_notification" value="true" <?php echo $check; ?>></input>
        <label>
        <?php echo esc_attr('Send notification on '.($post->post_status === 'publish' ? 'update' : 'publish') ); ?>
        </label>

    <?php
    }




    function save_notice_meta_box_data( $post_id ) {

        // Check if our nonce is set.
        if ( ! isset( $_POST['cabtv_notif_metabox'] ) ) {
            return;
        }

        // Verify that the nonce is valid.
        if ( ! wp_verify_nonce( $_POST['cabtv_notif_metabox'], 'cabtv_notif_metabox' ) ) {
            return;
        }

        // If this is an autosave, our form has not been submitted, so we don't want to do anything.
        if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) {
            return;
        }

        // Check the user's permissions.
        if ( isset( $_POST['post_type'] ) && 'page' == $_POST['post_type'] ) {

            if ( ! current_user_can( 'edit_page', $post_id ) ) {
                return;
            }

        }
        else {

            if ( ! current_user_can( 'edit_post', $post_id ) ) {
                return;
            }
        }

        /* OK, it's safe for us to save the data now. */

        // Make sure that it is set.
        if ( ! isset( $_POST['cabtv_send_notification'] ) ) {
            return;
        }

        // Sanitize user input.
        $my_data = sanitize_text_field( $_POST['cabtv_send_notification'] );

        // Update the meta field in the database.
        update_post_meta( $post_id, 'cabtv_notifications_sent', $my_data?$my_data:'');
    }

    add_action( 'save_post', 'save_notice_meta_box_data' );

**save_notice_meta_box_data function Code Explaination : **

// Check if our nonce is set.

if ( ! isset( $_POST['cabtv_notif_metabox'] ) ) {
    return;
}

// Check the user’s permissions.

if ( isset( $_POST['post_type'] ) && 'page' == $_POST['post_type'] ) {

        if ( ! current_user_can( 'edit_page', $post_id ) ) {
            return;
        }

    }
    else {

        if ( ! current_user_can( 'edit_post', $post_id ) ) {
            return;
        }
    }

// Make sure that it is set.

if ( ! isset( $_POST['cabtv_send_notification'] ) ) {
        return;
    }

// Update the meta field in the database.

 update_post_meta( $post_id, 'cabtv_notifications_sent',$my_data);

//Save post and page Hook

add_action( 'save_post', 'save_notice_meta_box_data' );