<?xml version="1.0" encoding="utf-8"?>
<odoo>
    <data>

        <record id="discount_account_invoice_view_form" model="ir.ui.view">
            <field name="name">discount.account.invoice</field>
            <field name="model">account.invoice</field>
            <field name="inherit_id" ref="account.invoice_form"/>
            <field name="arch" type="xml">
                <!-- This field is not showing up after -->
                <xpath expr="//field[@name='amount_untaxed']" position="after">
                    <field name="amount_discount"/>
                </xpath>

            </field>
        </record>
    </data>
</odoo>