Ошибка вращения AVAssetExportSession, когда видео с камеры

Я пытаюсь преобразовать видео .mov в .mp4 и заодно исправить ориентацию. Код, который я использую ниже, отлично работает при записи видео с помощью UIImagePickerController, однако, если видео выбрано из фотопленки, я получаю эту ошибку, и я не понимаю, почему:

Ошибка экспорта: Операция остановлена: Ошибка Домен = Код AVFoundationErrorDomain = -11841 «Операция остановлена» UserInfo = 0x1815ca50 {NSLocalizedDescription = Операция остановлена, NSLocalizedFailureReason = Не удалось создать видео.}

Я попытался сначала сохранить видео в другой файл, но это не помогло.

Вот код, который я использую для конвертации видео:

- (void)convertVideoToLowQuailtyAndFixRotationWithInputURL:(NSURL*)inputURL handler:(void (^)(NSURL *outURL))handler
{
    if ([[inputURL pathExtension] isEqualToString:@"MOV"])
    {
        NSURL *outputURL = [inputURL URLByDeletingPathExtension];
        outputURL = [outputURL URLByAppendingPathExtension:@"mp4"];

        AVURLAsset *avAsset = [AVURLAsset URLAssetWithURL:inputURL options:nil];

        AVAssetTrack *sourceVideoTrack = [[avAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
        AVAssetTrack *sourceAudioTrack = [[avAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];

        AVMutableComposition* composition = [AVMutableComposition composition];

        AVMutableCompositionTrack *compositionVideoTrack = [composition addMutableTrackWithMediaType:AVMediaTypeVideo
                                                                                    preferredTrackID:kCMPersistentTrackID_Invalid];
        [compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, avAsset.duration)
                                       ofTrack:sourceVideoTrack
                                        atTime:kCMTimeZero error:nil];
        [compositionVideoTrack setPreferredTransform:sourceVideoTrack.preferredTransform];

        AVMutableCompositionTrack *compositionAudioTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio
                                                                                    preferredTrackID:kCMPersistentTrackID_Invalid];
        [compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, avAsset.duration)
                                       ofTrack:sourceAudioTrack
                                        atTime:kCMTimeZero error:nil];

        AVMutableVideoComposition *videoComposition = [self getVideoComposition:avAsset];

        NSArray *compatiblePresets = [AVAssetExportSession exportPresetsCompatibleWithAsset:avAsset];
        if ([compatiblePresets containsObject:AVAssetExportPresetMediumQuality])
        {
            AVAssetExportSession *exportSession = [[AVAssetExportSession alloc]initWithAsset:composition presetName:AVAssetExportPresetMediumQuality];
            exportSession.outputURL = outputURL;
            exportSession.outputFileType = AVFileTypeMPEG4;
            exportSession.shouldOptimizeForNetworkUse = YES;
            exportSession.videoComposition = videoComposition;
            [exportSession exportAsynchronouslyWithCompletionHandler:^{

                switch ([exportSession status])
                {
                    case AVAssetExportSessionStatusFailed:
                        NSLog(@"Export failed: %@ : %@", [[exportSession error] localizedDescription], [exportSession error]);
                        handler(nil);

                        break;
                    case AVAssetExportSessionStatusCancelled:

                        NSLog(@"Export canceled");
                        handler(nil);

                        break;
                    default:

                        handler(outputURL);

                        break;

                }
            }];
        }

    } else {
        handler(inputURL);
    }
}

- (AVMutableVideoComposition *)getVideoComposition:(AVAsset *)asset
{
    AVAssetTrack *videoTrack = [[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
    AVMutableComposition *composition = [AVMutableComposition composition];
    AVMutableVideoComposition *videoComposition = [AVMutableVideoComposition videoComposition];
    CGSize videoSize = videoTrack.naturalSize;
    BOOL isPortrait_ = [self isVideoPortrait:asset];
    if(isPortrait_) {
//        NSLog(@"video is portrait ");
        videoSize = CGSizeMake(videoSize.height, videoSize.width);
    }
    composition.naturalSize     = videoSize;
    videoComposition.renderSize = videoSize;
    videoComposition.frameDuration = CMTimeMakeWithSeconds( 1 / videoTrack.nominalFrameRate, 600);

    AVMutableCompositionTrack *compositionVideoTrack;
    compositionVideoTrack = [composition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
    [compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, asset.duration) ofTrack:videoTrack atTime:kCMTimeZero error:nil];
    AVMutableVideoCompositionLayerInstruction *layerInst;
    layerInst = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoTrack];
    [layerInst setTransform:videoTrack.preferredTransform atTime:kCMTimeZero];
    AVMutableVideoCompositionInstruction *inst = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
    inst.timeRange = CMTimeRangeMake(kCMTimeZero, asset.duration);
    inst.layerInstructions = [NSArray arrayWithObject:layerInst];
    videoComposition.instructions = [NSArray arrayWithObject:inst];
    return videoComposition;
}