Make certain fields editable based SO Lines for closed order

This is almost a duplicate of this post 

https://community.acumatica.com/develop-customizations-288/make-certain-fields-editable-based-on-po-status-15192

I’ve tried the suggestions on that post but it is not resolving my issue.

I am trying to make two fields editable when the SO is CLOSED.  I’ve modified the Workflow as follows:

I added code as well:

namespace PX.Objects.SO
{
  public class SOOrderEntry_Extension : PXGraphExtension<PX.Objects.SO.SOOrderEntry>
  {
    #region Event Handlers
    protected void SOLine_RowSelected(PXCache cache, PXRowSelectedEventArgs e, PXRowSelected baseHandler)
    {
        baseHandler?.Invoke(cache, e);
        var row = (SOLine)e.Row;

        PXUIFieldAttribute.SetEnabled<FSxSOLine.sDSelected>(cache, row, true);
        PXUIFieldAttribute.SetEnabled<SOLine.requestDate>(cache, row, true);

    }
    #endregion
  }
}

The fields are still not editable.

I am thinking that the update cache option for the SO Lines is disabled for a closed order.  If that is the case, maybe there is no way to enable them.

Any suggestions?