I knew about Huma’s FBI testimony. What I didn’t know is that Crooked Hillary’s staff knew it was a problem and planned to discuss with the WH on the same day Gowdy issued a subpoena for the server.
March 4, 2015 – Hillary receives subpoena from House Select Committee on Benghazi instructing her to preserve and deliver all emails from her personal servers.
Well, it did destroy Obama's claim that he didn't know about it until he "heard it on the news". But, that didn't get much airtime.
Based on case law, they have a strong case for executive privilege, unless they can establish it was evidence of illegal activity (as Nixon learned, the hard way).