As you're using an iOS device, uninstall the app > restart the device > reinstall the app and try signing out & signing in back to see if that makes a difference? Keep us posted.
Appreciate you trying to fix the issue. As a next step, please login to the account/device experiencing the issue and send a feedback report: https://yt.be/help/g8TT . You may not get a response, but we do review everything and use the details to investigate and fix issues.