AVMutableComposition Merged Videos Not Saving in Correct Order - Swift 3

I am having trouble merging my videos in the correct order even though I am waiting for them to be done with a AVAsynchronousKeyValueLoading. The videos are playing back perfectly fine, but I can't the final result to show in the correct order.

At first I thought it was an issue with my videos being saved to the NSTemporaryDirectory, but I made sure that they were being saved correctly. (I can provide logs upon request).

Here is the order that I want the videos to playback in:

1st video --> 2nd video --> 3rd video

Here is the order that it is playing back in:

2nd video --> 1st video --> 3rd video

It works perfectly fine when I don't switch the camera though. Can anyone please help? It would be greatly appreciated and put me back on schedule for a production release of my app.

func mergeVideo()
  var mixComposition = AVMutableComposition()
  var resultMergedVideoTime = CMTime(seconds: 0, preferredTimescale: 1)
  var resultTrack = mixComposition.addMutableTrack(withMediaType: AVMediaTypeVideo, preferredTrackID: Int32(kCMPersistentTrackID_Invalid))

  let myGroup = DispatchGroup()

  for var i in 0..<self.resultVideoAssets.keys.count {
  myGroup.enter()
  let asset = Array(self.resultVideoAssets.keys)[i]
  asset.loadValuesAsynchronously(forKeys: ["playable"], completionHandler: {
  if asset.statusOfValue(forKey: "playable", error: nil) == .loaded {
  do {

  let videoDuration: CMTime = asset.duration
  let videoTrack = asset.tracks(withMediaType: AVMediaTypeVideo).first!
  var audioTrack:AVAssetTrack?
  if asset.tracks(withMediaType: AVMediaTypeAudio).count > 0 {
  audioTrack = asset.tracks(withMediaType: AVMediaTypeAudio).first
  }

  let timeRange = CMTimeRange(start: kCMTimeZero, duration: videoDuration)
  let audioCompTrack = mixComposition.addMutableTrack(withMediaType: AVMediaTypeAudio, preferredTrackID: Int32(kCMPersistentTrackID_Invalid))

  try resultTrack.insertTimeRange(timeRange, of: videoTrack, at: kCMTimeZero)
  resultTrack.preferredTransform = videoTrack.preferredTransform

  if let audioTrack = audioTrack {
  try audioCompTrack.insertTimeRange(timeRange, of: audioTrack, at: resultMergedVideoTime)
  }

  resultMergedVideoTime = CMTimeAdd(resultMergedVideoTime, videoDuration)

  } catch {
  //TODO: Error handler
  }
  }
  myGroup.leave()
  })
 }

  myGroup.notify(queue: .main) {
  let videoURL = NSURL(fileURLWithPath: NSTemporaryDirectory()).appendingPathComponent("mergeVideo\(arc4random()%1000)d")!.appendingPathExtension("mp4")
  let assetExport: AVAssetExportSession
  if #available(iOS 11.0, *) {
  assetExport = AVAssetExportSession(asset: mixComposition, presetName: AVAssetExportPresetHEVC1920x1080)!
  } else {
  assetExport = AVAssetExportSession(asset: mixComposition, presetName: AVAssetExportPreset1920x1080)!
  }
  assetExport.outputURL = videoURL
  assetExport.outputFileType = AVFileTypeMPEG4
  assetExport.shouldOptimizeForNetworkUse = true
  assetExport.exportAsynchronously {
  .........