The Android TV Hulu app is an old version that has not been updated in months. I signed up for HBO through Hulu, and I can't watch that through the Android TV app either. Fortunately, I had a spare Roku stick, and that has the latest Hulu app, so my wife and I are happily watching HBO on Hulu now.
Hulu isn't supporting Android TV anymore:
https://www.androidheadlines.com/2018/02/android-tv-hulu-live-tv-not-coming-due-to-lack-of-platform-users.html
The Android TV Hulu app is an old version that has not been updated in months. I signed up for HBO through Hulu, and I can't watch that through the Android TV app either. Fortunately, I had a spare Roku stick, and that has the latest Hulu app, so my wife and I are happily watching HBO on Hulu now.