Custom fields from ARInvoice not copied to GL Batch during release in Acumatica 24r1

I’m trying to transfer custom field values from ARInvoice (screen AR301000) to the GL Batch record created during release.

I added matching custom fields to both DACs via customization:

ARInvoice DAC fields:

• UsrCustomerExtContractNbr (nvarchar(30)) – N° contrat plateforme

• UsrCustomerExtJournal (nvarchar(30)) – Journal plateforme

• UsrCustomerExtRefNbr (nvarchar(30)) – N° de facture plateforme

Batch DAC fields:

• UsrExtContractNbr (nvarchar(30)) – N° contrat plateforme

• UsrExtJournal (nvarchar(30)) – Journal plateforme

• UsrExtRefNbr (nvarchar(30)) – N° de facture plateforme

I override the ARReleaseProcess.ReleaseDocProc method to handle the release logic, but when the batch is created, these custom fields remain blank in the GL Batch record.

Question:
Why aren’t the custom fields from ARInvoice being transferred to the GL Batch during release?

Here is ARReleaseProcess graph code:

using System;
using System.Collections.Generic;
using PX.Data;
using PX.Objects.AR;
using PX.Objects.GL;
using Cegid.Erp;

namespace PX.Objects.AR
{
    public class ARReleaseProcess_Extension : PXGraphExtension<ARReleaseProcess>
    {
        public delegate List<ARRegister> ReleaseDocProcBasicDelegate(
            JournalEntry je, ARRegister ardoc, List<Batch> pmBatchList);

        [PXOverride]
        public List<ARRegister> ReleaseDocProc(
            JournalEntry je, ARRegister ardoc, List<Batch> pmBatchList,
            ReleaseDocProcBasicDelegate baseMethod)
        {
            List<ARRegister> result = baseMethod(je, ardoc, pmBatchList);

            if (ardoc == null || je == null || je.BatchModule.Current == null)
                return result;

            ARInvoice arInvoice = PXSelect<ARInvoice,
                Where<ARInvoice.docType, Equal<Required<ARInvoice.docType>>,
                And<ARInvoice.refNbr, Equal<Required<ARInvoice.refNbr>>>>>
                .Select(Base, ardoc.DocType, ardoc.RefNbr);

            if (arInvoice == null)
                return result;

            var arExt = arInvoice.GetExtension<ARRegisterExt>();
            var batchExt = je.BatchModule.Current.GetExtension<BatchExt>();

            if (arExt != null && batchExt != null)
            {
                batchExt.UsrExtContractNbr = arExt.UsrCustomerExtContractNbr;
                batchExt.UsrExtJournal = arExt.UsrCustomerExtJournal;
                batchExt.UsrExtRefNbr = arExt.UsrCustomerExtRefNbr;

                je.BatchModule.Update(je.BatchModule.Current);
            }

            return result;
        }
    }
}