Hi Eduardo.
In Jmix 2.x when you open editor this way it is opened as new web page. In this case you should set reference manually or provide parent object to the new page and handle it.
If you want to create\edit some nested object within parent object in the same web page you should open nested editor in dialog mode. In this case reference will be set automatically
Add the following property to target action:
<action id="create" type="list_create">
<properties>
<property name="openMode" value="DIALOG"/>
</properties>
</action>
Regards,
Ivan