AudioKit: AKOfflineRenderNode doesn't render any sound.

I utilized AKOfflineRenderNode to process recorded voice. The idea is to record voice and save it into the file. Next apply some effects to this file and save combined voice+effects into file.

I have successful result on my iPhone 6s running on iOS 11.0.3 but on other devices running on iOS 11+(for example last generation of iPad on 11.0.3) I always have “silent” file with same size about 60 Kb. I attached one for reference(rec.zip). Also the issue 100% reproducible on iOS 11 simulator.

Here is my setup(I removed effects setup since offline render doesn’t work even on clean recording):

    fileprivate func setupAudioKit(){
        AKSettings.enableLogging = true
        AKAudioFile.cleanTempDirectory()
        
        AKSettings.bufferLength = .medium
        AKSettings.numberOfChannels = 2
        AKSettings.sampleRate = 44100
        AKSettings.defaultToSpeaker = true
        
        do {
            try AKSettings.setSession(category: .playAndRecord, with: .allowBluetoothA2DP)
        } catch {
            AKLog("Could not set session category")
        }
        
        mic = AKMicrophone()
        micMixer = AKMixer(mic)
        
        recorder = try? AKNodeRecorder(node: micMixer)
        
        if let file = recorder.audioFile {
            player = try? AKAudioPlayer(file: file)
            player.looping = true
        }
        playerMixer = AKMixer(player)
// Effects setup
        offlineRenderer = AKOfflineRenderNode(playerMixer)
        AudioKit.output = offlineRenderer

        AudioKit.start()
}

Here is export method:

     fileprivate func render() {
        offlineRenderer.internalRenderEnabled = false
        player.schedule(from: 0, to: player.duration, avTime: nil)
        
        let renderURL = URL(fileURLWithPath: FileHelper.documentsDirectory() + "rec.m4a")
        
        let sampleTimeZero = AVAudioTime(sampleTime: 0, atRate: AudioKit.format.sampleRate)
        player.play(at: sampleTimeZero)
        do {
            try offlineRenderer.renderToURL(renderURL, seconds: player.duration)
        } catch {
            print(error)
        }
        player.stop()
        offlineRenderer.internalRenderEnabled = true
    }