It's not possible to add a new translation to a Landing page Content Item - the editor throws an error about not being able to find a siteacess

Setup:
1. Add a new Language in the admin panel - "Polski" (pol-PL)
2. Set up YAML files (config/packages/ibexa.yaml and config/packages/ibexa_admin_ui.yaml) so that the site and admin_group siteaccesses use the new language:

            languages: [eng-GB, pol-PL]

Steps to reproduce:
1. Login as admin
2. Go to Content -> Content structure
3. Switch to Translations tab and select "Add new"
4. Select "English" as base and "Polski" as target
5. Click "Create"

Expected result:
Page Builder editor opens. It's possible to add a new translation.

Actual result:
Page Builder does not open, the following exception is shown:

NoMatchingSiteAccessFoundException

Ibexa\Contracts\PageBuilder\Exception\NoMatchingSiteAccessFoundException:

  at vendor/ibexa/page-builder/src/lib/Siteaccess/Selector/SiteAccessSelector.php:36
  at Ibexa\PageBuilder\Siteaccess\Selector\SiteAccessSelector->selectSiteAccess(object(Context), array())
     (vendor/ibexa/page-builder/src/bundle/Controller/PageController.php:309)
  at Ibexa\Bundle\PageBuilder\Controller\PageController->editAction(object(Request), object(ContentEditView))
     (vendor/symfony/http-kernel/HttpKernel.php:163)

Notes: