Some off-the-shelf themes don't show metadata on single view

[imsimond]

I have just installed a completely fresh WordPress 4.1.1 install (default language French, if that's relevant); downloaded Babble as a ZIP from Hithub, and installed it. I have then translated the initial 'Hello World' post from French into another installed language.

In certain themes, on single.php-based output, metadata such as date and author name isn't being shown on the translation.

Twenty Fifteen, Twenty Fourteen, Twenty Thirteen or Sela are all affected. Curiously, the Syntax theme is not.

The original default post: note it shows a date and username below

A translation into English (US): no date/username is shown