I stopped getting "statistics" part, from 06-April-2017, It was working perfectly fine and now for several videos I am not getting "statistics" part. when I make this call, https://www.googleapis.com/youtube/v3/videos?part=statistics&key=validKey&id=3cxixDgHUYw
FYI, I also tried getting "statistics" part from here, but not receiveing it. https://developers.google.com/youtube/v3/docs/videos/list
Same issue as well, someone has opened up an issue at Google's issue tracker here