Even after changing the settings in /admin/config/system/site-information, the page title still contains "Drupal".
All external examinations of the site configuration (config table and exported files) show the new name.
I examined the function template_preprocess_html() in theme.inc (where the configuration value is supposed to be loaded and entered in the theme variables), and inserted the following var_dumps:
var_dump(\Drupal::config('system.site')->getRawData()['name']);
var_dump(\Drupal::config('system.site')->get('name'));
var_dump(\Drupal::config('system.site')->getOriginal('name'));
The resulting output is string(12) "My Site Name" string(6) "Drupal" string(6) "Drupal".
The configuration value isn't overridden anywhere in the site's settings files either. All caches are cleared.
Why is ->get('name') returning the wrong value even though ->getRawData() contains the correct one?
Edit: I should probably add that this is a site with a non-English default language. That seems to be the cause of nearly all the configuration-related core bugs. However, the langcode of the sytem.site configuration entity is correctly set.
Edit: More digging reveals that the language module is indeed responsible for overriding the configured name with the default name.
Edit3: There doesn't appear to be a way to set the localized site information without editing the configuration externally. I exported it, deleted the file language/de/system.site.yml and re-imported, which fixed it. (In the production site, importing didn't remove the deleted configuration entity; I had to delete the language.de/system.site record from the config table directly.)
