It’s important to remember that James Clapper left his position on January 20, 2017. Since that time he has been a private citizen, and not privy to the ongoing investigations or information that has come to light since then. Certainly a lot of new information about trump/Russia collusion has been uncovered in recent months. In fact, some of the investigations and investigatory committees have started since that date. Clapper himself has occasionally mentioned that date, but the media almost never seem to highlight it.