Reproduce the bug

1. create a global user (fill the first name and last name)
2. create a subwiki (import the default xwiki XAR) with the new user as a member
3. login as the new user (don't forget to give him a password)
4. create a document in the subwiki (for the example, Sandbox/FooBar)
5. create another document (for the example, Sandbox/LiveTableProblem) with the following code

       {{documents space='Sandbox' /}}
   

You should see in the 'last author' column that the document 'Sandbox/FooBar' only display the login of the user, not the prettyname.

The same procedure but in the main wiki works well.

What I have found

The livetable is calling getLocalUserName inside the LiveTableResultsMacros page for doc.author and doc.creator.