How can I set the Value to NULL when configuring a rule in Data Access Group for Sales Orders ?

Summary:

We want to restrict the creation and update of sales orders for specific order types. To achieve this, we configured Data Access Group for Sales Orders as shown in the attached screenshot.

Since we want to allow the creation of return orders, we tried creating a return order with this configuration. However, we encountered a 404 error.

We assume this is because the Order Type is NULL when a return order is created. Is our assumption correct?

Also, is it possible to add a condition in Data Access Group for Sales Orders Rules to handle cases where the Order Type is NULL?