RPScreenRecorder not recording mic on iOS 12

Why won't RPScreenRecorder record the mic, even though it is enabled, if the permissions popup doesn't appear? It works when the popup appears but attempts after restarting the app don't record the mic. here's the very simple app i made just to test this feature for a larger app.

I have tested this exact application on iOS 11 and it works every time.

However on iOS 12+ it only works when the permission popup appears and that's every 8 minutes. It should work every time after giving permissions.

import UIKit
import ReplayKit


class ViewController: UIViewController, RPPreviewViewControllerDelegate {
    private let recorder = RPScreenRecorder.shared()
    private var isRecording = false


    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
    }


    @IBAction func react() {
        if !isRecording {
            let alert = UIAlertController(title: "Record", message: "Would you like to record a video?", preferredStyle: .alert)
           
            let okay = UIAlertAction(title: "Okay", style: .destructive, handler: { (action: UIAlertAction) in
                self.startRecording()
            })
           
            alert.addAction(okay)
            self.present(alert, animated: true, completion: nil)
        } else {
            stopRecording()
        }
    }
   
    private func startRecording() {
       
        guard self.recorder.isAvailable else {
            print("Recording is not available at this time.")
            return
        }
        self.recorder.isMicrophoneEnabled = true
       
        self.recorder.startRecording{ [unowned self] (error) in
            guard error == nil else {
                print("There was an error starting the recording.")
                return
            }
           
            print("Started Recording Successfully")
            self.isRecording = true
           
        }
       
       
    }
   
    private func stopRecording() {
        recorder.stopRecording { [unowned self] (preview, error) in
            print("Stopped recording")
            guard preview != nil else {
                print("Preview controller is not available.")
                return
            }
           
            let alert = UIAlertController(title: "Recording Finished", message: "Would you like to edit or delete your recording?", preferredStyle: .alert)
           
            let deleteAction = UIAlertAction(title: "Delete", style: .destructive, handler: { (action: UIAlertAction) in
                self.recorder.discardRecording(handler: { () -> Void in
                    print("Recording suffessfully deleted.")
                })
            })
           
            let editAction = UIAlertAction(title: "Edit", style: .default, handler: { (action: UIAlertAction) -> Void in
                preview?.previewControllerDelegate = self
                self.present(preview!, animated: true, completion: nil)
            })
           
            alert.addAction(editAction)
            alert.addAction(deleteAction)
            self.present(alert, animated: true, completion: nil)
           
            self.isRecording = false
        }
    }
   
    func previewControllerDidFinish(_ previewController: RPPreviewViewController) {
        dismiss(animated: true)
    }
   
}