If you go to a Portfolio Item's score card, it's unclear how the Un-estimated % is calculated.

It appears to be an average of un-estimated for the subs (Features to Capabilities to Epics or whatever the hierarchy is).

This puts unnecessary scrutiny on some initiatives. For example:

I have an epic where one feature is 87% un-estimated (13 backlog items) but at the epic rollup it shows 40% un-estimated. This is a it unfair as the rollup is 13 stories un-estimated out of 50 (which would be 26%).