Hi,

Seems the code is missing from the question due to the issues in the forum. The issue here might be you are inheriting the the sale order form itself and referring to the newly added field in it. Here the the newly added field is not in the sale order form view(original view, it is in inherited view). 

So instead of inheriting the sale order form, inherit the view that adds the field x_studio_delivery_note or refer to a field existing in the corresponding view.

Thanks