German article is not visible in English folder on Sub-items List but is on Content Tree.

Steps:

1. Create a Folder with only English translation.
2. Create an Article with only German translation inside this folder.
3. View the folder in admin UI on Content tab.

Actual result: Article is visible on Content Tree. Article is not visible on Sub-items List.
Expected result: Supposedly Article should be visible on SIL after adding German translation to the folder and switching to German in admin. Which doesn't work. And what is more, is not required on 2.5.6.