HummingBird is not minifying the files its keep on showing pending

HummingBird is not minifying the files its keep on showing pending

Error message from wp-smush-pro

Error message
E_WARNING: Invalid argument supplied for foreach()

Stack trace
…called at /var/www/html/wp-content/plugins/wp-smush-pro/lib/
class-wp-smush.php (1507)
…called at /var/www/html/wp-content/plugins/wp-smush-pro/lib/
class-wp-smush.php (940)
… at /var/www/html/wp-content/plugins/wp-smush-pro/lib/
class-wp-smush-admin.php (1054)
… at /var/www/html/wp-content/plugins/wp-smush-pro/lib/
class-wp-smush-admin.php (219)
in WpSmushitAdmin::filter_attachment_fields_to_edit called at ? (?)
in call_user_func_array called at /var/www/html/wp-includes/plugin.php (235)
in apply_filters called at /var/www/html/wp-admin/includes/media.php (1655)
in get_compat_media_markup called at /var/www/html/wp-includes/media.php (3184)
in wp_prepare_attachment_for_js called at ? (?)
in array_map called at /var/www/html/wp-admin/includes/ajax-actions.php (2388)
in wp_ajax_query_attachments called at ? (?)
in call_user_func_array called at /var/www/html/wp-includes/plugin.php (525)
in do_action called at /var/www/html/wp-admin/admin-ajax.php (89)