The files generated using AVAudioRecorder have a constant size of only 4kb

Hello. My app uses AVAudioRecorder to generate recording files, which are consistently only 4kb in size. Most users generate audio files normally, with only a few users experiencing this phenomenon occasionally. After uninstalling and installing the app, it will work normally, but it will reappear after a period of time. I have compared that the problematic audio files generated each time are fixed and cannot be played. Added the audioRecorderDidFinishRecording proxy method, which shows that the recording was completed normally. The user also reported that the recording is normal, but there is a problem with the generated file. How should I handle this issue? Look forward to your reply.

- (void)startRecordWithOrderID:(NSString *)orderID {
    AVAudioSession *audioSession = [AVAudioSession sharedInstance];
    [audioSession setCategory:AVAudioSessionCategoryRecord error:nil];
    [audioSession setActive:YES error:nil];
    NSMutableDictionary *settings = [[NSMutableDictionary alloc] init];

    [settings setObject:[NSNumber numberWithFloat: 8000.0] forKey:AVSampleRateKey];
    [settings setObject:[NSNumber numberWithInt: kAudioFormatLinearPCM] forKey:AVFormatIDKey];
    [settings setObject:[NSNumber numberWithInt:16] forKey:AVLinearPCMBitDepthKey];
    [settings setObject:[NSNumber numberWithInt: 1] forKey:AVNumberOfChannelsKey];
    [settings setObject:[NSNumber numberWithBool:NO] forKey:AVLinearPCMIsBigEndianKey];
    [settings setObject:[NSNumber numberWithBool:NO] forKey:AVLinearPCMIsFloatKey];
    
    NSString *path = [WDUtility createDirInDocument:@"audios" withOrderID:orderID withPathExtension:@"wav"];
    NSURL *tmpFile = [NSURL fileURLWithPath:path];
    recorder = [[AVAudioRecorder alloc] initWithURL:tmpFile settings:settings error:nil];
    [recorder setDelegate:self];
    [recorder prepareToRecord];
    [recorder record];
}