Why did the Jewish leaders leave after meeting with Paul in Rome?
The Jewish leaders departed because they could not agree among themselves. After Paul spoke, citing Isaiah's prophecy that they would hear but not understand, no consensus was reached. Their disagreement ended the meeting, so they left Paul under house arrest in Rome.
The context shows Paul was in Rome under house arrest awaiting justice after appealing to Caesar. He told the Jewish leaders he had nothing to accuse his nation of and had called them to speak with him because for the hope of Israel he was bound in this chain. When they met with him, they agreed not among themselves and departed; they could not agree on anything. Paul had spoken one word, going back to the Old Testament and quoting the Holy Spirit by Isaiah: "Go to this people, and say, Hearing you shall hear, and not understand." Their inability to agree followed that message.
And when they agreed not among themselves, they departed, after that Paul had spoken one word, Well spake the Holy Ghost by Esaias the prophet unto our fathers,