This page describes a known limitation where Quality rules cannot be created through Assessment Model by setting computing configuration to 'Computing based on Scope and Property'.
This particular feature of creating a quality rule with computing configuration set to 'Computing based on Scope and Property' is not supported by the product yet.
This limitation is already documented in CMS-Help (CAST > CAST Management Studio > How To > Create a new Quality Rule).
If the option is chosen, validation error is thrown in the validation view regarding missing Total scope name and missing Detail property.
Note: This is planned to be supported in 7.2 in the context of Set Management.