Clear the Youtube app's data. Try again.
Factory reset
Slight Threadjacking: I was just checking and is it possible to log in to multiple accounts on youtube yet? (profiles) I see you can do it on the apple tv. I have Smart Youtube tv logged in to a different account but this seems ridiculous for Google's own native android tv app to be behind apple tvs version
Fantastic story, brother.
I had the same problem 2 weeks ago and it was fixed by setting the date/time to sync automatically in android tv settings.