I don't think the question has been answered, and I have it too. I already know how to get a list of blocked work. Those are the blockEEs. I want to record the blockERs, to track their resolution and also to see patterns of obstacles.
For example, if four stories are blocked because a key person in IT is on a three-week vacation, I would like that fact recorded in a list I could refer to in the future. And if it happened every sprint with some other key resource, I would like to be able to record that fact to present to the teams so they could visualize the systemic impediment and try to resolve it.
Listing the blocked stories, or even the blocking history, is simply not good enough.
Of course I could create a new Project for impediment resolution and then user stories, but identifying them as impediments would be more useful and less confusing.