3184808 - Error: "Document Failed during HTTP/SOAP post for Customer"

In the Ariba Integration, the RemittanceImportAsyncRequest documents are failing in the Managed Gateway Transaction Tracker.

Document Failed during HTTP/SOAP post for Customer XXX - Realm Name XXX and received SOAP Fault Message: java.lang.Exception: java.lang.Exception: SOAP Fault :The incoming message is invalid with the following errors: urn:Ariba:Buyer:vrealm_XXX:RemittanceImportAsync@ line 31 in SoapResponseParse.groovy. Suggested Action : For further assistance, please contact Managed Gateway for Spend&Network Support with Error Code : CIG-PLT-04641

Downloading the Validator.dat file reveals the below error:

The incoming message is invalid with the following errors:

cvc-datatype-valid.1.2.1: '' is not a valid value for 'dateTime'
cvc-datatype-valid.3.1.3: The value '' of element 'urn:PayableDate' is not valid.  

or

Remittance export, failing, failed, tracker, Document failed during HTTP/SOAP post, RemittanceImportAsync, CIG , KBA , BNS-ARI-CI-BUY , Managed Gateway for Procurement , BNS-ARI-CI-SCC-BUY , Managed Gateway for Buyer Business Network SCC , Problem