Primary menu item does not expand when set to front

I have a menu item which is set to <front>. It has subitems and the menu item has been set to expand. However, when the front page is viewed, the menu item does not select nor expand. A workaround is to set the menu item to "node".

Drupal's menu system should threat <front> the same as node (or whatever the front page is) so that the behaviour is the same.