Long operation while executing UpdateIN on Process Shipment screen (SO503000) never finish

Hi all

I overrode the button UpdateIN in SOShipmentEntry to add additional logic related to transfers. When I execute the action opening a single confirmed shipment (Screen SO302000), it works as expected. But when invoked from the Process Shipments screen SO503000 (action Update IN), the long operation in the base graph never returns and the execution enters in an eternal wait. This is an excerpt of the overridden code:

[PXOverride]
public IEnumerable updateIN(PXAdapter adapter, List<SOShipment> shipmentList, updateINDelegate baseMethod)
{
	List<SOShipment> shipments = shipmentList ?? adapter.Get<SOShipment>().ToList();

	try
	{				
		bool isTransfer = shipments.Any(a => a.ShipmentType == SOShipmentType.Transfer);
		...

		if (isTransfer)
		{					
			...
		}

		var retVal = baseMethod?.Invoke(adapter, shipmentList);

		if (isTransfer)
		{
			// CODE GET STUCK HERE
			PXLongOperation.WaitCompletion(Base.UID);					

			...
		}
	}
	catch (PXException ex)
	{
		PXTrace.WriteError(ex);
	}

	return adapter.Get();
}

I am basically passing over the same adapter with the list of shipments. What am I missing?