As in question. I'm following this tutorial: https://dev.acquia.com/blog/debugging-drupal-8/debugging-twig-templates-in-drupal-8-with-phpstorm-and-xdebug/25/08/2016/16586
is always empty
I'v tried cr all, checked file system page, did drush cron, checked theme page - no errors.
I got some errors related to permissions at theme settings page, but:
chmod 777 -R sites/default/files
seems to solved those.