Group fields not saving in Gutenberg

Other fields are working good but, group’s sub fields doesn’t save on post update.

function my_theme_share_button_block_fields() {
	acf_add_local_field_group(
		array(
			'key'      => 'group_share_button',
			'title'    => esc_html__( 'Share Button', 'text-domain' ),
			'fields'   => array(
				array(
					'key'   => 'field_share_title',
					'label' => esc_html__( 'Title', 'text-domain' ),
					'name'  => 'title',
					'type'  => 'text',
				),
				array(
					'key'           => 'field_share_title_tag',
					'label'         => esc_html__( 'Title Tag', 'text-domain' ),
					'name'          => 'title_tag',
					'type'          => 'select',
					'choices'       => array(
						'h1'   => 'h1',
						'h2'   => 'h2',
						'h3'   => 'h3',
						'h4'   => 'h4',
						'h5'   => 'h5',
						'h6'   => 'h6',
						'p'    => 'p',
						'span' => 'span',
					),
					'default_value' => 'h2',
				),
				array(
					'key'        => 'field_share_button',
					'label'      => esc_html__( 'Button', 'text-domain' ),
					'name'       => 'button',
					'type'       => 'group',
					'layout'     => 'row',
					'sub_fields' => array(
						array(
							'key'   => 'field_share_button_text',
							'label' => esc_html__( 'Text', 'text-domain' ),
							'name'  => 'button_text',
							'type'  => 'text',
						),
						array(
							'key'   => 'field_share_button_url',
							'label' => esc_html__( 'Url', 'text-domain' ),
							'name'  => 'button_url',
							'type'  => 'url',
						),
						array(
							'key'          => 'field_share_button_title_attr',
							'label'        => esc_html__( 'Title', 'text-domain' ),
							'name'         => 'button_title',
							'type'         => 'text',
							'instructions' => esc_html__( 'The title attribute.', 'text-domain' ),
						),
						array(
							'key'   => 'field_share_button_new_tab',
							'label' => esc_html__( 'New Tab', 'text-domain' ),
							'name'  => 'button_new_tab',
							'type'  => 'true_false',
							'ui'    => true,
						),
					),
				),
			),
			'location' => array(
				array(
					array(
						'param'    => 'block',
						'operator' => '==',
						'value'    => 'acf/my-theme-share-button',
					),
				),
			),
			'active'   => true,
		)
	);
}

add_action( 'acf/init', 'my_theme_share_button_block_fields' );

WordPress: 5.6
ACF Pro: 5.9.3

Server info:

Start by reproducing the Gutenberg block field registration shown in the report with WordPress 5.6 and ACF Pro 5.9.3, focusing on the acf/init registration and the group field's sub_fields. Done means the group subfields retain their values after the post is updated.