Steps to reproduce

1. Go to PlatformUI;
2. Create a new language on "Admin panel -> Languages" to ensure two languages at least on your installation; (because of EZP-25078, reload the page)
3. On default landing page content "eZ Platform", create a content of any content type (doesn't matter);
4. On editing context, on the top right corner, at the language switcher, the default language for PlatfomUI should show through its Language Name: "English (United Kingdom)". Click on "(change)"
5. From the list of languages available, choose other than the default one, and click "Confirm". The language switcher will now display the new language as expected, but showing its language code instead of the language name.
6. Changing back to the original language maintains the same behaviour henceforth: language name ceases to show at all.