In Classic we have the Risk Rating page. These risk factors are mapped to the Risk Categories on individual Risk instances. When creating individual risks, after you select the category it locks down that risk factor on the risk rating page. Going forward all updates are made via individual risks.
In the MUX it does not lock down the risk factor (it remains editable). A users could then change it to whatever they want and the tool never syncs it back up.
However, if you add one of these fields to a blueprint, the field is editable in MUX.
In Classic the Investment's Risk Rating page has Categories such as
Once you create a Risk on the project and assign it to one of these categories the Risk Rating Category becomes read only.
Adding these fields to your blueprint will allow you to edit them in MUX which then updates the value in Classic.
Release : 16.0.2
In order to make the field read only from the Blueprint would be to apply a business rule to it.