Second language option for administrators is not available

Updated: Comment #1

Problem/Motivation

Administrators are supposed to have a field on their profile page to set a second langugage, but that field doesn't show up.

Steps to reproduce

Installed modules: Languages, Content, Interface and Configuration Translation, on a fresh D8 install.
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Proposed resolution

?

Remaining tasks

• look into instructions from #1998648: "Administration pages language" user account setting should be hidden if not used, and verify bug
• add exact steps to reproduce (https://drupal.org/contributor-tasks/add-steps-to-reproduce)

User interface changes

No.

API changes

No.