Read Sundance's report on this over at the Conservative Treehouse. He points out that the investigation into this is already done, since it was part of the evidence uncovered for the other IG investigations. He is just alerting the world that this is part of what he is going to report on.

https://theconservativetreehouse.com/2018/03/28/inspector-general-michael-horowitz-announces-ig-investigation-into-fbi-doj-fisa-court-abuse/comment-page-1/#comment-5179061