Wrong display of users when using default value for userpicker

Trying to use a user picker widget with velocity macro and a default value, I noticed that the user image and name wasn't displayed in such case.
Reproduction steps:

• On a wiki with user XWiki.Foo defined
• Create a page with following code:

  {{velocity}}
  {{html}}
  #set ($userPickerParams = {
                    'name': 'approverUser',
                    'id': 'approverUser',
                    'class': 'form-control',
                    'value': ['XWiki.Foo'],
                    'data-userScope': 'LOCAL_AND_GLOBAL'
                  })
                  #userPicker(true, $userPickerParams)
  {{/html}}
  {{/velocity}}
  

Expected result:

• The user picker should contain a value displaying the user Foo with its name and picture

Obtained result:

• the picker contain a text 'XWiki.Foo' (see screenshot)

Also note that even when removing the value (backspace) and searching "Foo" in the picker, it never displays properly the user.