This is a political game Republicans are playing in order to distract from the legal troubles of former Pres. Donald Trump, the GOP's presumptive nominee for president. Republicans received a transcript of Hur's interview and their pursuit of the recordings is just part of the off-the-wall conspiracy theories they have to sell to their followers to distract from their deficiencies.
This isn't about politics, it's about an attorney general who believes he's above the law and an administration that's doing all it can to obfuscate this situation. A recording is always superior evidence to a transcript, and Congress has a right to hear what Hur said as part of their investigation into the president's possible crimes or incompetence. Besides, the president lost executive privilege when he released the transcript.