Not to be insulting, this is my read on things. congress, meaning both parties, have given mueller full reign to bring down Trump. Any expectation that the IG report will do anything but further that ignores reality. This is a political witch hunt that will end in some kind of dirt that ether discredits Trump, or sees his impeachment. My current conspiracy theory is that the tax bill will be defeated, the markets will crash, mueller will indict a bunch people around Trump, maybe even bring bogus charges against Trump, and the media will convince America that it is Trumps fault.
Inspector General Michael Horowitz like Rod Rosenstein, the Deputy Attorney General, were appointed by Obama. They were in positions of authority during the most corrupt administration in American history. If you think they will faithfully serve the Trump administration I have a bridge you might be interested in. The Trump administration is plagued with moles. The Deep State has the same problem. It releases information only when it knows it is coming out anyway. The Deep State has dirt on everyone. Even people who support Trump must bow to their wishes or be destroyed. If they don’t have dirt they will create it. Think of Judge Moore.