Update: Looks like this issue is isolated to Android and only a handful of specific cases. We're continuing to monitor reports to get this fixed!https://twitter.com/TeamYouTube/status/987041038844874752 …
Have you tried clearing your browser's cache and cookies? Here's how: https://goo.gl/dwzcyo . Also, try using different browser or Incognito mode. This usually clears things up but let us know if it's still not working!