Of course did not tell Schiff. You are not suppose to warn the enemy that you are coming.
The real difference between what John Durham is doing and what Adam Schiff is doing is that John Durham is following the legal processes of gathering evidence, presenting it to a grand jury comprised of ordinary citizens, obtaining indictments based on their collective wisdom, and building a real case that must stand up in a US court. Adam Schiff is prosecuting a President with no articulated crime, no evidence of wrong doing, and in secret with no review by actual citizens. Its the difference between a legitimate use of prosecutorial power and a political hit job by a hack politician.