I added a many2many relation to sale.order.line to one of my model, when i select the value the proper value show, but upon pressing on save, another value gets recorded

in model: 

allocate_order_line_to = fields.Many2one('sale.order.line', ondelete='cascade')

in form view:

<field name="allocate_order_line_to" options="{'no_create_edit': True, 'no_create': True, 'no_quick_create': True}" />

Before saving: https://ibb.co/HBbVvHw

After saving: https://ibb.co/kJpN182

If anyone has an idea of either the sale.order.line model having a special behavior, or way to troubleshoot where the new id is coming from, loosing our mind over it