Steps to reproduce

1. Create a new language e.g.  Polish
2. Create a new site access with only the added language
3. Go to any landing page and translate it to the added language
4. Preview landing page
5. Try change to added siteaccess

Result

Currently, preview only works with main language and it is not possible to change the language or siteaccess to another one that does not contain main language content.

Expected

It should at least be possible to select other siteaccesses in which the content will be displayed regardless of the language