While creating planned transfer orders with different dates, different order date and delivery date were given. While firming the Planned transfer orders ‘Grouping = Month’ selected. Transfer order is created with one header and multiple lines against each order. But transfer order lines created with same order date and same delivery date.

As per Bug, The desired behavior is currently not supported. Setting the same delivery date across all lines of an order is a consistent experience when firming planned transfer or purchase orders with Group By Period.