To reproduce:
- Log in to Library Card.
- Select Hebrew as the user interface language in the Profile page. Click "Set language". The language changes to Hebrew.
- Log out.
- Open a private browser window.
- Log in to Library Card with the same account you used in earlier steps.
Observed: The user interface language is English.
Expected: The user interface language is supposed to be Hebrew.
Bonus step: Check the language definition on the Profile page. The selected language is Hebrew! So the language is stored correctly in the preferences, but the preference is not actually used unless you click "Set language" again.