We'd like to help. 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. Also, could you try re-uploading the video to see if that makes a difference? Let us know.
Thanks for trying those steps. As a next step, please login to the account/device experiencing the issue and send a feedback. Here's how: https://yt.be/help/feedback . You may not receive an individual response, but the details will help us identify and fix any issues.