I have a m2m field in my custom module, in the py file i have these:

product = fields.Many2many('stock.quant', string="Product")

in the xml:

<notebook>

    <page string="Product">

          <field name="product" options="{'no_open':True, 'no_quick_create': True, 'no_create_edit': True, 'no_create': True}" domain="[('lot_id','!=', context.get('lot_id', False)), ('state', '=', 'buffer')]">

                   <tree open="false" editable="bottom">

                         <field name="product_id"/>

                          <field name="lot_id"/>

                          <field name="state" />   

                   </tree>

          </field>

    </page>

</notebook>

It works fine when i add an item but when I started editing the state column of the m2m to active, after clicking the Save button, the item disappears in the form. I have a screenshot below:

1st

https://pasteboard.co/GL3pDg2.png

2nd

https://pasteboard.co/GL3pMHs.png

3rd (the item disappeared after saving)

https://pasteboard.co/GL3pTKJ.png