@TeamYouTube why can't I see those videos which I am adding them to playlists?? Whenever I go through my playlist to see the video but it's not there. It says "Playlist has been edited" and can't find the newly added videos.
Please fix this.

That's odd! What device are you on? If you're on a browser, try clearing the cache and cookies or uninstalling the app, if you're on a mobile device. Keep us posted.