Steps to reproduce

1. Configure default SiteAccess as following:

       siteaccess:
           list: [site]
           groups:
               site_group: [site]
           default_siteaccess: site
           match:
               URIElement: 1
   ...
       system:
           site_group:
           ...
               languages: [fre-FR, eng-GB]
           ...
   

2. Add language French (fre-FR) in the backoffice.
3. Reload the whole application (I recommend to use hard reload) in the browser
4. Try to create a new article using Create button located in the right, upper corner of the dashboard. You should see a form for creating the object and the selected language is English.
5. Discard changes and go to the Content Structure.
6. Try to create a new article using Create button from the right menu.
   You should see a form for creating the object and the selected language is French.

Current behavior:
The selected language in the form on the dashboard is English.

Expected behavior:
The language of the form on the dashboard should be the first language defined in the SiteAccess configuration as it is in case of the form in Content Structure.