Export mapping not working after upgrade to Mendix 6

Hi, I am upgrading an application from 5.16.1 to 6.10.10. During the upgrade I encountered a problem with the export mapping and I am unable to solve it thus far.   In the picture you can see a part of the export mapping where it goes wrong. First I tried to solve this problem with the initial mapping, but I failed so I let Mendix automatically generate the mapping and this is the result. All objects are required, so I created new objects to export. Although when I try to actually run the export mapping it gives an error that an object is empty, while I am certain it is created and the right association is set. Could anyone please advice how to solve this problem? I already looked into the documentation and tried different possible solutions, but still the same errors comes up. Also the documentation doesn't give such a complex example as this one. The error message is as follows:  Exporting an empty object is not allowed when element is neither optional nor nillable (urn:rosettanet:specification:interchange:ShipmentStatusDistribution:xsd:schema:01.03:ShipmentStatusDistribution|urn:rosettanet:specification:interchange:ShipmentStatusDistribution:xsd:schema:01.03:ShipmentStatus|urn:rosettanet:specification:interchange:ShipmentStatusDistribution:xsd:schema:01.03:ShipmentInformation|urn:rosettanet:specification:interchange:ShipmentStatusDistribution:xsd:schema:01.03:RoutingInformation|urn:rosettanet:specification:domain:Logistics:xsd:schema:01.12:ProofOfDeliveryInformation|urn:rosettanet:specification:domain:Logistics:xsd:schema:01.12:ReceivedBy|urn:rosettanet:specification:universal:PartnerIdentification:xsd:schema:01.04:SpecifiedFullPartner^urn:rosettanet:specification:universal:PartnerIdentification:xsd:schema:01.04:SpecifiedFullPartnerType)
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