Why can't I debug twig templates with intellij idea? I can't get intellij idea to break on twig files. It is breaking on theme and module files fine. This means that xdebug must be setup correctly. I don't believe that it is caching as I've deleted the cache files 

drush ev '\Drupal\Core\PhpStorage\PhpStorageFactory::get("twig")-&gt;deleteAll();'
The problem was that the twig cache path was not set for the project. 

See https://blog.jetbrains.com/phpstorm/2019/05/twig-and-blade-templates-debugging-2/