The field 'Retail return reason code' is available on the Sales Return line details, and this field worked in all scenarios before the recent upgrade to Finance & SCM version 10.0.21 (10.0.960.79).

Now, after upgrading, when a return order line is entered but there is no original sales order (invoiced) that is linked to the sales return, the system clears out the value entered by the user and replaces the reason code with blank.

If the sales return has been linked to an original invoiced sales order, the field respects the value entered by the user and it is not replaced with blank.

This reason code Line details field should work the same whether the sales return is linked to an invoiced sales order or not, and whether or not the Retail module with call centers is used.