Updating SharePoint Online items using SOAP/XML API from outside of SharePoint

we are having a lot of trouble updating our SharePoint Online list from an external system using SOAP/XML.

The system had no problems working with our old On-Premises SharePoint 2010 lists, but we have migrated to SharePoint Online

Here is the SOAP BODY of the Request:

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:soap="http://schemas.microsoft.com/sharepoint/soap/">
   <soapenv:Header/>
   <soapenv:Body>
      <soap:UpdateListItems>
         <soap:listName>REDACTED</soap:listName>
         <soap:updates>
            <Batch OnError="Continue" ListVersion="1" ViewName="REDACTED">
   <Method ID="1" Cmd="Update">
      <Field Name="ID">1002</Field>
      <Field Name="Received">1</Field>
      <Field Name="COMSBarcode">RL101150</Field>
      <Field Name="DateReceived">2020-03-03</Field>
      <Field Name="ReceivedBy">andras boros</Field>
      <Field Name="DefectsFaults" />
      <Field Name="Description">This is Box 20/1</Field>
   </Method>
   <Method ID="2" Cmd="Update">
      <Field Name="ID">1003</Field>
      <Field Name="Received">1</Field>
      <Field Name="COMSBarcode">RL101151</Field>
      <Field Name="DateReceived">2020-03-03</Field>
      <Field Name="ReceivedBy">andras boros</Field>
      <Field Name="DefectsFaults" />
      <Field Name="Description">This is Box 20/2</Field>
   </Method>
   <Method ID="3" Cmd="Update">
      <Field Name="ID">1004</Field>
      <Field Name="Received">1</Field>
      <Field Name="COMSBarcode">RL101152</Field>
      <Field Name="DateReceived">2020-03-03</Field>
      <Field Name="ReceivedBy">andras boros</Field>
      <Field Name="DefectsFaults" />
      <Field Name="Description">This is Box20/3</Field>
   </Method>
</Batch>
         </soap:updates>
      </soap:UpdateListItems>
   </soapenv:Body>
</soapenv:Envelope>

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here is the error response:

{TL:DR}

main error is

                  <ErrorCode>0x81020026</ErrorCode>
                  <ErrorText>The list that is referenced here no longer exists.</ErrorText>

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the entire response is:

<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
   <soap:Body>
      <UpdateListItemsResponse xmlns="http://schemas.microsoft.com/sharepoint/soap/">
         <UpdateListItemsResult>
            <Results>
               <Result ID="1,Update">
                  <ErrorCode>0x81020026</ErrorCode>
                  <ErrorText>The list that is referenced here no longer exists.</ErrorText>
                  <z:row 
					ows_Title="I changed it online (Andras Boros)" ows_T_x002d_Code="X91" 
					ows_BoxNo="20.0000000000000" 
					ows_DeliveryMethod="DPD" ows_SealNumber="0" ows_PreferredCollectionDate="2020-03-16 00:00:00" ows_Description="This is Box 20/1" 
					ows_Category="Art and Pictures" ows_GiftAidID="0" ows_StoreValuation="32.1000000000000" 
					ows_Status="Printed" 
					ows_Comments="Yes I can update it" 
					ows_Received="0" ows_ContentTypeId="0x0100FCC93A269C890F47BFFFC8289D8F819A" 
					ows_ItemsQty="3.00000000000000" 
					ows_LabelSent="0" 
					ows_LinkTitleNoMenu="I changed it online (Andras Boros)" ows_LinkTitle="I changed it online (Andras Boros)" ows_LinkTitle2="I changed it online (Andras Boros)" ows_ParcelForce="1" 
					ows_ToteBox="0" 
					ows_ProcessLocked="0" 
					ows_TillCode="8891" 
					ows_eBayRef="8891-00020" 
					ows_ID="1002" 
					ows_ContentType="Item" 
					ows_Modified="2020-03-03 15:52:26" 
					ows_Created="2020-03-03 10:44:07" 
					ows_Author="1723;#James Tullett" 
					ows_Editor="15103;#Benjamin Edwards" 
					ows_owshiddenversion="5" 
					ows_WorkflowVersion="1" 
					ows__UIVersion="512" 
					ows__UIVersionString="1.0" 
					ows_Attachments="0" 
					ows__ModerationStatus="0" 
					ows_SelectTitle="1002" 
					ows_Order="100200.000000000" 
					ows_GUID="{REDACTED GUID}" 
					ows_FileRef="1002;#teams-and-projects/MyRetail_HUB/ebayit/Lists/eBayIT_TrackMySales/1002_.000" 
					ows_FileDirRef="1002;#teams-and-projects/MyRetail_HUB/ebayit/Lists/eBayIT_TrackMySales" 
					ows_Last_x0020_Modified="1002;#2020-03-03 10:44:07" 
					ows_Created_x0020_Date="1002;#2020-03-03 10:44:07" 
					ows_FSObjType="1002;#0" 
					ows_SortBehavior="1002;#0" 
					ows_PermMask="0x7fffffffffffffff" 
					ows_FileLeafRef="1002;#1002_.000" 
					ows_UniqueId="1002;#{F9332E59-566B-4E35-BBB6-827A4D0EBF28}" 
					ows_ProgId="1002;#" 
					ows_ScopeId="1002;#{46DF5C67-9142-47D0-8208-A427C2C402E0}" 
					ows__EditMenuTableStart="1002_.000" 
					ows__EditMenuTableStart2="1002" 
					ows__EditMenuTableEnd="1002" 
					ows_LinkFilenameNoMenu="1002_.000" 
					ows_LinkFilename="1002_.000" 
					ows_LinkFilename2="1002_.000" 
					ows_ServerUrl="/teams-and-projects/MyRetail_HUB/ebayit/Lists/eBayIT_TrackMySales/1002_.000" 
					ows_EncodedAbsUrl="https://SERVER/SUSBSITE/TEAMSITE/ebayit/Lists/eBayIT_TrackMySales/1002_.000" 
					ows_BaseName="1002_" 
					ows_MetaInfo="1002;#" 
					ows__Level="1" 
					ows__IsCurrentVersion="1" 
					ows_ItemChildCount="1002;#0" 
					ows_FolderChildCount="1002;#0" 
					ows_Restricted="1002;#" 
					ows_OriginatorId="1002;#" 
					ows_NoExecute="1002;#0" 
					ows_ContentVersion="1002;#0" 
					ows__ComplianceFlags="1002;#" 
					ows__ComplianceTag="1002;#" 
					ows__ComplianceTagWrittenTime="1002;#" 
					ows__ComplianceTagUserId="1002;#" 
					ows_AccessPolicy="1002;#" 
					ows__VirusStatus="1002;#" 
					ows__VirusVendorID="1002;#" 
					ows__VirusInfo="1002;#" 
					ows_SMTotalSize="1002;#444" 
					ows_SMLastModifiedDate="1002;#2020-03-03 15:52:26" 
					ows_SMTotalFileStreamSize="1002;#0" 
					ows_SMTotalFileCount="1002;#0" 
					xmlns:z="#RowsetSchema"/>
               </Result>
              <CUT>
            </Results>
         </UpdateListItemsResult>
      </UpdateListItemsResponse>
   </soap:Body>
</soap:Envelope>

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so what are we missing here?