Interesting that they also mention the 2 letters Grassley sent in October to the FBI and DOJ. In the second letter, Grassley states that DOJ wouldn't give him classified info that was mentioned in the IG report because it would interfere with Mueller investigation but the topic was the Mid-Year Investigation which relates to HRC,

https://www.judiciary.senate.gov/press/rep/releases/grassley-seeks-information-about-fbi-raid-of-whistleblowers-home