PI 7.3: MessageID set by SOAP Sender

Hello,

the following URL is used by a SOAP client to set the messageID in a scenario using PI 7.3:

http://< host name>:<port name>/XISOAPAdapter/MessageServlet?senderParty=<name of the sender party>&senderService=<name of the sender service>&interface=<name of the interface>&receiverParty=<name of the receiver party>&receiverService=<name of the receiver service>&interfaceNamespace=<name of the interface namespace>&MessageId=<GUID>

However the MessageId in the URL is ignored and another GUID is set by PI? Has anyone been able to set client specific messageIDs in SOAP scenarios on PI 7.3?

I have checked the help section to ensure that the URL syntax is correct.

Checkboxes "Use encoded headers" and "Use Query String" are activated in the corresponding SOAP sender channel too.

Thank you for your advice.