Enable Twig debug doesn't work? Why isn't the Twig debug working on my Drupal 8.2.6 site?

This is the folder structure.



These are the folder permissions.



This is the content of the settings.php file.

$settings['hash_salt'] = 'DEVELOPMENT_SALT';
$settings['update_free_access'] = FALSE;
$settings['file_public_base_url'] = 'http://localhost/files';
$settings['file_public_path'] = 'sites/default/files';
$settings['file_private_path'] = 'sites/default/private';
$settings['file_scan_ignore_directories'] = [
  'node_modules',
  'bower_components',
];
if (file_exists(__DIR__ . '/../development/settings.development.php'))     {
  include __DIR__ . '/../development/settings.development.php';
}


Here I include /../development/settings.development.php.

assert_options(ASSERT_ACTIVE, TRUE);
\Drupal\Component\Assertion\Handle::register();

/**
 * Enable local development services.
 */
$settings['container_yamls'][] = __DIR__ . '/development.services.yml';

$databases['default']['default'] = array(
  'database' =&gt; 'dbname',
  'username' =&gt; 'dbusername',
  'password' =&gt; 'pw',
  'prefix' =&gt; '',
  'host' =&gt; '127.0.0.1',
  'port' =&gt; '3306',
  'namespace' =&gt; 'Drupal\\Core\\Database\\Driver\\mysql',
  'driver' =&gt; 'mysql',
);

$settings['hash_salt'] = 'DEVELOPMENT';

$config['system.logging']['error_level'] = 'verbose';
$config['system.performance']['css']['preprocess'] = FALSE;
$config['system.performance']['js']['preprocess'] = FALSE;
$settings['cache']['bins']['render'] = 'cache.backend.null';
$settings['cache']['bins']['dynamic_page_cache'] =     'cache.backend.null';
$settings['extension_discovery_scan_tests'] = TRUE;
$settings['rebuild_access'] = TRUE;
$settings['skip_permissions_hardening'] = TRUE;


Here I also add development.services.yml.

parameters:
  http.response.debug_cacheability_headers: true
  twig.config:
    debug: true
    auto_reload: true
    cache: false
services:
  cache.backend.null:
    class: Drupal\Core\Cache\NullBackendFactory


Things I have checked/done:


Checked if all these files are loaded -> They are
Checked the indentation of the development.services.yml -> Checks out
Cleared all the different caches, rebuild them, etc -> If I change a template, it changes, but no Twig debugging


sites/default/files AND sites/default/private are not used by Drupal.
Try to change your development.services.yml to following. this  works for me correctly(I hope works for you too) .  

services:
  cache.backend.null:
    class: Drupal\Core\Cache\NullBackendFactory

# Enable Twig debugging.
parameters:
 twig.config:
   debug: true
   auto_reload: true
   cache: false


also  this article about setting up debugging on Drupal 8 is very good for future visitors of this question.