Bandwidth Optimization options locked I'm running a largely default Drupal 8.0.0-RC2 site. At /admin/config/development/performance the "Bandwidth Optimization" settings for "Aggregate CSS Files" and "Aggregate Javascript files" are disabled, so I cannot change their state. Extensive though fruitless googling suggests this is unusual, but I'm stumped on where to start. I'm using the Drude environment for my site.
There is a problem with the public directory, it is not configured or it is not writable. You can check this with drush:

drush ev "var_dump(is_dir('public://'), is_writable('public://'))"


Result should be:

    bool(true)
    bool(true)


If these two conditions are true, then the checkboxes will be available.