Because of [this](https://github.com/l3pp4rd/DoctrineExtensions/blob/master/lib/Gedmo/Translatable/TranslatableListener.php#L441). It does not passes since $locale and $this->defaultLocale have same value, so it does not translate. 
So, in order to work, you must pick base locale (eg English), and it loads translated values only if current locale is different from base locale.