AVMutableVideoComposition & AVVideoCompositionCoreAnimationTool color glitch - ios

Question

I'm trying to add image to video using following code:
AVURLAsset* videoAsset = [[AVURLAsset alloc]initWithURL:[self assetURL] options:nil];
AVMutableComposition *mixComposition = [[AVMutableComposition alloc] init];
AVMutableCompositionTrack *videoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
[videoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration)
ofTrack:[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0]
atTime:kCMTimeZero error:nil];
AVMutableCompositionTrack *audioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
[audioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration)
ofTrack:[[videoAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0]
atTime:kCMTimeZero error:nil];
AVMutableVideoCompositionInstruction *mainInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
mainInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, videoAsset.duration);
AVMutableVideoCompositionLayerInstruction *videolayerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoTrack];
AVAssetTrack *videoAssetTrack = [[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
[videolayerInstruction setTransform:videoAssetTrack.preferredTransform atTime:kCMTimeZero];
mainInstruction.layerInstructions = [NSArray arrayWithObjects:videolayerInstruction,nil];
AVMutableVideoComposition *mainCompositionInst = [AVMutableVideoComposition videoComposition];
CGSize naturalSize = CGSizeApplyAffineTransform(videoTrack.naturalSize, videoTrack.preferredTransform);
mainCompositionInst.renderSize = naturalSize;
mainCompositionInst.instructions = [NSArray arrayWithObject:mainInstruction];
mainCompositionInst.frameDuration = CMTimeMake(1, 30);
CGFloat ratio = naturalSize.width / rectVideo.size.width;
CALayer *parentLayer = [CALayer layer];
CALayer *videoLayer = [CALayer layer];
parentLayer.frame = CGRectMake(0, 0, naturalSize.width, naturalSize.height);
videoLayer.frame = CGRectMake(0, 0, naturalSize.width, naturalSize.height);
[parentLayer addSublayer:videoLayer];
for(DraggableImageView *iv in imageViews){
CALayer *overlayLayer = [CALayer layer];
[overlayLayer setContents:(id)[[self normalizedImage:iv.image] CGImage]];
overlayLayer.frame = CGRectMake(iv.frame.origin.x * ratio, (rectVideo.size.height - iv.frame.origin.y - iv.frame.size.height) * ratio, iv.frame.size.width * ratio, iv.frame.size.height * ratio);
[overlayLayer setMasksToBounds:YES];
overlayLayer.opacity = 0;
overlayLayer.masksToBounds = YES;
CGFloat duration = CMTimeGetSeconds(iv.endTime) - CMTimeGetSeconds(iv.startTime);
CGFloat start = CMTimeGetSeconds(iv.startTime);
if(duration > CMTimeGetSeconds(videoAsset.duration)){
duration = CMTimeGetSeconds(videoAsset.duration);
start = 0;
}
CGFloat fadeInSeconds = iv.fadeInSeconds;
CGFloat fade = fadeInSeconds / duration;
CAKeyframeAnimation *anim = [[CAKeyframeAnimation alloc] init];
anim.keyPath = #"opacity";
anim.values = #[#0, #1, #1, #0];
NSMutableArray *keyTimes = [NSMutableArray new];
[keyTimes addObject:#0];
[keyTimes addObject:#(fade)];
[keyTimes addObject:#(1.0 - fade)];
[keyTimes addObject:#1];
anim.keyTimes = keyTimes;
anim.duration = duration;
anim.beginTime = AVCoreAnimationBeginTimeAtZero + start;
[overlayLayer addAnimation:anim forKey:#"anim"];
[parentLayer addSublayer:overlayLayer];
}
mainCompositionInst.animationTool = [AVVideoCompositionCoreAnimationTool
videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:videoLayer inLayer:parentLayer];
NSURL *exportURL = [self exportUrl];
exportSession = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetHighestQuality];
exportSession.outputURL = exportURL;
exportSession.videoComposition = mainCompositionInst;
exportSession.outputFileType = _recordSession.fileType;
exportSession.timeRange = CMTimeRangeMake(kCMTimeZero, videoAsset.duration);
exportProgressTimer = [NSTimer scheduledTimerWithTimeInterval:.1 target:self selector:#selector(exportDidProgress:) userInfo:nil repeats:YES];
[exportSession exportAsynchronouslyWithCompletionHandler:^{
switch (exportSession.status) {
case AVAssetExportSessionStatusCompleted:
[self savingComplete:exportSession.error];
break;
case AVAssetExportSessionStatusFailed:
[self savingComplete:exportSession.error];
break;
case AVAssetExportSessionStatusCancelled:
break;
default:
break;
}
}];
This code works great on iPhone SE but on iPad Air 2 gives this color glitch on the right edge of video (zoomed screenshot):
This glitch is not static, it changes vertically (size and y position).
I think this is not a problem with video size (well known problem with green line on the edge when video size not dividable by 4 or 16). Size of this video is 1080x1920.
Any ideas?