That's odd. While clearing your browser's cache and cookies clears things up on desktop, updating or reinstalling the app often fixes most issues on your mobile device. Let us know how it goes.
Appreciate the info. Please send a feedback report directly from YouTube with these steps: https://goo.gl/WdI0BK . While every individual report may not get a direct response, we do review everything and use the details to investigate and fix issues. Thanks!