Objects that have been added outside of the Scenario Designer and do not correspond to the defined assignment rules are placed below the "Unassigned" structure item. Even if the button for assignment rules has been activated in the toolbar of the Scenario Designer and the added object does not correspond to any rule, the object is first inserted below the Unassigned structure element. These objects are highlighted in orange and won't be included in the documentation if you export the scenario.
If these unassigned objects should be part of the export, they must be inserted into the regular structure of the Scenario. You can either create appropriate assignment rules for this (context menu of the structure item), or you can insert the objects manually into the structure.
The unassigned objects can be automatically assigned to the corresponding chapter via the context menu as follows: