It could be the following
1. The Top Secret Classified information may be “Eyes Only” and too sensitive for anyone to see
2. The FBI is trying to contain this and defuse the scandal for the US, and protect Hillary
3. They are working directly for Loretta Lynch, who has decided she wants a conviction.
4. Hillary is blackmailing the FBI director, and the FBI is trying to get her first
Another option, very unlikely, but it would be the best scenario:
Career FBI and Intelligence officials are fed up with Hillary’s dangerous games and for once, are doing their job, in defiance of pressure they’re receiving from their superiors.