You have add label_translator_strategy: sonata.admin.label.strategy.underscore in the service definition:
sonata.admin.user:
class: Application\Sonata\UserBundle\Admin\TestAdmin
tags:
- { name: sonata.admin, manager_type: orm, group: users, label: users, label_translator_strategy: sonata.admin.label.strategy.underscore }
arguments:
- null
- Application\Sonata\UserBundle\Entity\User
- SonataAdminBundle:CRUD
calls:
- [setTranslationDomain, [SonataUserBundle]]
- [setUserManager, [@fos_user.user_manager]]
- [setSecurityContext, [@security.context]]
I have tested in a new project, and it works fine.