@TeamYouTube have all notification options checked properly and STILL am not receiving notifications for comments to me and replies to me on my iPhone app. I do get some, but not all. Happens too often. Need to fix the comment/ reply area of app!
Thanks for reaching out. If you're getting a lot of comments on a video, you may not receive notification for every single comment, we'll send you occasional notifications instead. Hope this helps clarify.