Previewing Landing Page draft in PageBuilder will display its parent.

Steps to reproduce:
1. Clean installation of eZ Platform 2.5
2. Create a new Landing Page inside Home Content.
3. Fill all required fields for a Landing Page inside Page Builder, and from the dropdown menu choose "Save Draft".
4. Toggle from Edit mode to Preview mode using toggle (the Eye icon).

Result
Parent content will be displayed as a preview.

Expected Result
Previously saved Draft should be displayed.