In what circumstances have the courts found the prosecution failed to exercise reasonable diligence in subpoenaing a witness at a preliminary hearing?

In contrast, in People v. Cromer (2001) 24 Cal.4th 889 (Cromer), a case cited by the majority, the court found the prosecution did not exercise reasonable diligence. The witness testified at a preliminary hearing under subpoena, but two weeks later, law enforcement reported that she was no longer at the same address. Despite this information, the prosecution made no effort to serve subpoenas to secure the witness's attendance until six months later, only weeks before the trial was set to begin. Investigators went to the witness's house, but she was not there. Eventually, a man at the witness's former home told the investigators the witness was living with her mother in San Bernardino. Two days later they went to the mother's home, but were told the mother would return the following day. An investigator left a subpoena for the witness, but neither returned to speak to the witness's mother, nor attempted to find other ways to contact the mother.