muk_base/muk_attachment_lobject/views/ir_attachment.xml

<?xml version="1.0" encoding="UTF-8"?>

<!--

    Copyright (c) 2017-2019 MuK IT GmbH.

    This file is part of MuK Large Objects Attachment 
    (see https://mukit.at).

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with this program. If not, see <http://www.gnu.org/licenses/>.

  -->

<odoo>


<record id="view_attachment_form" model="ir.ui.view">
	<field name="name">ir_attachment.form</field>
    <field name="model">ir.attachment</field>
    <field name="inherit_id" ref="base.view_attachment_form"/>
    <field name="arch" type="xml">
        <xpath expr="//group[@name='storage']" position="inside">
        	 <group string="Storage" name="storage" groups="base.group_no_one">
                  <field name="store_lobject" readonly="1" attrs="{'invisible':[('store_lobject','=',False)]}"/>
              </group>
        </xpath>
    </field>
</record>

</odoo>