A check for Netflix
Use a title you have already played in the same account on another device. If it starts there and the TV lists it without playing, save the error shown by the TV. If the title is missing from both menus, start at the title and profile controls rather than resetting the television.
Check on the intended screen
Open the app catalogue on your actual device and confirm the publisher and region. Sign in only through the service or documented billing issuer.
Keep a title-level test
Use one title, episode or fixture that you can identify. Record whether the app launches, the account signs in and the item plays.