I have a special process that creates MO's based on BOM's from a task. 

In v10, this worked just fine.

mo_vals = {'product_id': product_id,
                           'bom_id': bom.id,                        
                           'product_uom_id': bom.product_uom_id.id,
                           'product_qty': bom.product_qty,
                           'sale_id': self.sale_id.id,
                           'task_id': self.id,
                            }
self.env['mrp.production'].create(mo_vals)

However in v13, when the MO is created, it does not populate the components (move_raw_ids)

It looks like the _onchange_bom_id that add the move_raw_ids on the MO is not being called when the record is being created. 

How do you call _onchange_bom_id at time of creation or even after?