API: query delivery per recipient returns 404

Hi all! I am working on an integration with our customer service, to allow them to see deliveries sent to customers when they look them up in an external system they have available.  

The call to get deliveries for a recipient based on an internal ID is not working anymore. It worked and the integration worked like a charm, but not for longer than 1 day, and now all I get is a 404 in response from the API which seems very strange to me. I am not sure which logs to look in to debug this further, so I am currently pretty stuck and just wondering why it all of a sudden stopped working when it did work at some point, hmm. 

I was hoping that some from the community have ideas to how I can proceed this investigation? 

cURL example of the call itself:

curl --location --request POST 'https://tv2-mkt-prod1.campaign.adobe.com/jsp/soaprouter.jsp' \
--header 'Content-Type: text/xml' \
--header 'SOAPAction: xtk:queryDef#ExecuteQuery' \
--header 'X-Security-Token: XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX \
--header 'cookie: __sessiontoken=XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX' \
--data-raw '<soapenv:Envelopexmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"xmlns:urn="urn:xtk:queryDef">
    <soapenv:Header/>
    <soapenv:Body>
        <urn:ExecuteQuery>
            <sessiontoken>XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX</sessiontoken>
            <urn:entity>
                <queryDefoperation="select"schema="nms:broadLogRcp"lineCount="10">
                    <select>
                        <nodeexpr="@eventDate"/>
                        <nodeexpr="[delivery/@label]"/>
                        <nodeexpr="[delivery/@id]"/>
                        <nodeexpr="@status"/>
                        <nodeexpr="@controlGroupMember"/>
                        <nodeexpr="@id"/>
                        <nodeexpr="@campaignName"/>
                        <nodeexpr="[delivery/mailParameters/subject]"/>
                    </select>
                    <where>
                        <conditionexpr="[recipient/@email] = '\''x@y.dk'\''"/>
                    </where>
                    <orderBy>
                        <nodeexpr="@eventDate"sortDesc="true"/>
                    </orderBy>
                </queryDef>
            </urn:entity>
        </urn:ExecuteQuery>
    </soapenv:Body>
</soapenv:Envelope>'