I can't say for sure, but the actions of his attorneys appear to indicate he is not happy with Schiff. He probably believed the promise of anonymity.
In what Country does a person accusing another of a Crime that he didn't personally have knowledge of, not have to testify under oath. If the President is in fact their " Defendant" in this charade. Then he has the right to face his Accuser and cross examine him with or without the assistance of counsel . However, Donald Trump is not the Defendant, The 63,000,000 people who voted him into Office are. And under that surmise "We the People" get to face him and have him cross examined by Counsel " Congressmen and women. Everyone should know his name. Answer questions written form? Not in our Court System , because, there is no guarantee the witness would be the one answering the questions now is there. Stand up brave CIA operative ! 65,000,000 people are waiting with bated breathe for your sworn testimony. "I don't know" is not an answer ! And Jeffery Epstein is still alive. He's hanging out with Elvis.