When viewing Landing Page Content Object in the backoffice (from Content Structure panel) there is a request being sent to "/studio/urlalias/xxx". It contains "X-Siteaccess" header that sets siteaccess for this request. Currently, this header is always set to the first siteaccess from project configuration. It should be either "default_siteaccess" or the siteaccess from UI.
Sending always the first siteaccess from the list can cause bugs when this siteaccess has a specific configuration. For example, in customer's case, this siteaccess was using different Entity Manager and different database than the one from UI, which caused errors.

Steps to reproduce:
1. Install ezplatform-ee.
2. Execute php app/console ezplatform:install studio-clean
3. In the file app/config/ezplatform.yml, on the line 13 enter any second siteaccess (ex. "second_siteaccess") as the first one on the list. After the change this fragment should look like this:

    siteaccess:
        list:
          - second_siteaccess
          - site

4. Clean cache and login to the backoffice with "Network" tab open from Chrome DevTools
5. Go to Content/Content structure
6. Find in the "Network" tab request that looks like this: http://ezplatform-ee.dev/studio/urlalias/0-d41d8cd98f00b204e9800998ecf8427e
7. Check request headers. It shows: "X-Siteaccess:second_siteaccess" despite the fact that UI siteaccess is set to "site" and default_siteaccess is also set to "site".