Unable to update PreferredDeliveryMethod as Null using SOAP Service

Hi Team,

We are trying to update PreferredDeliveryMethod as Blank/Null using soap service. We are getting status as Succeeded but changes are not reflecting. If we try to update other values, it is reflecting in UI.

Endpoint URL:https://*********************/fscmService/ReceivablesCustomerProfileService

Request:

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:typ="http://xmlns.oracle.com/apps/financials/receivables/customers/customerProfileService/types/" xmlns:cus="http://xmlns.oracle.com/apps/financials/receivables/customers/customerProfileService/" xmlns:cus1="http://xmlns.oracle.com/apps/financials/receivables/customerSetup/customerProfiles/model/flex/CustomerProfileDff/" xmlns:cus2="http://xmlns.oracle.com/apps/financials/receivables/customerSetup/customerProfiles/model/flex/CustomerProfileGdf/">