WebService Consumer can't send XOP object - Status 900 org.apache.axis2.AxisFault: Received a plain text response

Hello, im using WebMethods Service Designer v10.5 to create a consumer and import a service . This service has a XOP object as input, it is used to submit documents as XOP objects.

When importing the service, the Enable MTOM streaming for elements of type base64Binary option was set.

The IS has the following extended settings:

watt.server.SOAP.MTOMStreaming.cachedFiles.location=temp/mtom/cachedfiles
watt.server.SOAP.MTOMStreaming.enable=true
watt.server.SOAP.MTOMStreaming.threshold=500000
watt.server.SOAP.MTOMThreshold=500000

I’ve tried obtaining the file as a Base64Binnary String and as a Stream, and then using the pub.soap.utils:createXOPObject to create the object.

When sending the object generated, in both use cases, the response we get back is always:

SOAP 900 - Error occurred while processing SOAP response
org.apache.axis2.AxisFault: Received a plain text response:

If the XOP object attachment is not fullfilled the request goes through and we get a response from the service we are calling:
SOAP Error 500 - Attachment not fullfiled , which leaves the conclusion the problem is in the XOP object sent.

Using the exact same soap request in SOAP UI, with same headers and definitions, we get success and are able to submit the documents.

In debug mode we see the XOPObject is null but using the pub.soap.utils:getXOPObjectContent we see the data is there in run time.

In the image bellow we see the transport info from the SoapClient request

Any help on how to overcome this issue? I have made a lot of different implementations, and the error is always the same

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