Workflow Editor Production Order Maintenance Screen "Unknown Status"

Hello ​@bwhite49, Based on my debugging, it seems like the issue is caused by StatusID check happening in AMProdItem_RowDeleting event which leads to the error. Overriding the event to avoid the validation for your custom statuses as below would fix this error:

protected virtual void AMProdItem_RowDeleting(PXCache cache, PXRowDeletingEventArgs e, PXRowDeleting basemethod)
        {
            var amProdItem = (AMProdItem)e.Row;
            if (amProdItem == null)
            {
                return;
            }

            if (amProdItem.Hold.GetValueOrDefault())
            {
                throw new PXSetPropertyException(Messages.GetLocal(Messages.ProdStatusDeleteInvalid, Messages.Hold));
            }
            if (!(amProdItem.StatusID.EqualsWithTrim("Q") || amProdItem.StatusID.EqualsWithTrim("W") || amProdItem.StatusID.EqualsWithTrim("E")))
            {
                if (!amProdItem.StatusID.EqualsWithTrim(ProductionOrderStatus.Planned))
                {
                    var label = ProductionOrderStatus.GetStatusDescription(amProdItem.StatusID.TrimIfNotNullEmpty().ToUpper());
                    throw new PXSetPropertyException(Messages.GetLocal(Messages.ProdStatusDeleteInvalid, label));
                }
            }
            if (!Base.IsContractBasedAPI && !Base.IsImport && !Base.IsImportFromExcel)
            {
                var relatedOrders = Base.relatedProdOrders.Select().RowCast<AMProdItemRelated>().ToList();
                if (relatedOrders.Any())
                {
                    string[] relatedOrderNumbers = relatedOrders.Select(s => $"{s.OrderType} - {s.ProdOrdID}").ToArray();
                    if (Base.relatedProdOrders.Ask(
                      Messages.DeleteProductionOrderTitle,
                      Messages.GetLocal(Messages.LinkedOrderAllocationDeleteConfirmation, string.Join(", ", relatedOrderNumbers)), MessageButtons.YesNo) != WebDialogResult.Yes)
                    {
                        e.Cancel = true;
                        return;
                    }
                }
            }

            if (Base.ContainsSOReference)
            {
                AMConfigurationResults confRow = Base.ItemConfiguration.SelectWindowed(0, 1, new object[] { amProdItem });

                if (!Base.IsImport)
                {
                    if (Base.ProdMaintRecords.Ask(Messages.ConfirmDeleteTitle, Messages.ConfirmSOLinkedOrderDelete, MessageButtons.YesNo) != WebDialogResult.Yes)
                    {
                        e.Cancel = true;
                    }
                }
                if (confRow != null && e.Cancel == false)
                {
                    //We don't want to delete the Configuration if it's still linked with a SOLine
                    PXParentAttribute.SetLeaveChildren<AMConfigurationResults.prodOrderNbr>(Base.Caches[typeof(AMConfigurationResults)], null, true);

                    //We want to remove the linked with the defunct production order.
                    confRow.ProdOrderType = null;
                    confRow.ProdOrderNbr = null;
                    this.Base.ItemConfiguration.Update(confRow);
                }
            }

            if (ProductionTransactionHelper.ProductionOrderHasUnreleasedTransactions(this.Base, amProdItem, out var unreleasedMsg))
            {
                throw new PXException(unreleasedMsg);
            }

        }

Hope this helps!