Hi Claudio,
What you describe is a corruption where objects have an empty master locale.
This might happen after upgrade from 70.x versions or when transporting content from 7.0x versions to 7.3x versions.
Assuming you have an updated version SAP has a support tool which can be used only be Development Support to correct this and fix all corrupted objects in the system assigning them the Master Locale that fits your needs.
You can ofcourse to it manually for each object using the PCD Inspector tool but it might be painfull if you have many such objects.
Please open a support request for SAP describing the issue as well as my response here on the BC-PIN-PCD component.
Best Regards,
Dror.