Hello Nikita,

The field ‘Warehouse’ is not storable field that’s why you’re not able to save the value for it, If you make it storable from backend side(Python) then you can save value for it.
e.g.
Py:
class ProductTemplate(models.Model):
_inherit = 'product.template'

warehouse_id = fields.Many2one('stock.warehouse', store=True)

hope this can help you.

Thanks & Regards,
Email: odoo@aktivsoftware.com
Skype: kalpeshmaheshwari