Hay @TeamYouTube what's going on with mobile??? It seems there's a bug where videos won't appear for the first few minutes of the video being live but if you click on the notification it'll play fine??
We haven't receive any reports like that, can you confirm if you have the latest version of the app? You can try to reinstall it, or clear your cache and cookies. Here's how: https://yt.be/help/Cko1 . Let us know how that goes!