I think you may need to work with Support to get the right Disposition to type into the Wrap-up rule.
Per the Resource Center at https://help.mypurecloud.com/articles/add-rule/
Call Analysis—is available when you set the type to Wrap-up Code. It allows you to perform an action when call analysis detects a busy signal, answering machine, live person, or the when the call is not answered. For example, you can set the rule action to schedule a callback in 10 minutes if a line is busy.
The Disposition box allows you to select Busy, Machine, No Answer, or Person. In special cases, you may type a free-form call analysis condition instead. For example, you might type disposition.classification.callable.sit. The ability to enter free-form disposition strings is intended for limited use by customers with special requirements, as instructed by product support personnel. This feature supports any call analysis disposition that PureCloud Edge may return.
It might work if you try disposition.classification.uncallable.sit but that is just a guess, and if it doesn't work you can contact Support.