I18n not working on admin https pages

Hello,

I have set up a bilingual English(default)-Greek site, with plain http access for visitors and https access for the admin, using the SecurePages module (7.x-1.0-beta2). The admin pages are https-only, while normal nodes can be accessed by the administrator both in http and https modes.

The problem is that while translations (menus, vocabularies, fields, nodes etc) work as expected on the http pages, they do not work on https. Https returns only the English pages, even if I select Greek, either from the language switcher or by adding the el/ prefix to the path.

Drupal version is 7.38. On the server, SSL has been set up by using apache's mod_ssl module and a self-signed certificate.

Thanks in advance