LOL!
"Hey Siri" is only supposed to work if you say the words when you are connected to a power source. Is your TV saying those words. . . Without power source Siri is activated when you hold the home button for an extra long time.
I don't particularly need something to respond to my voice, so I have not activated it. I may give it a try to test and see if I have a similar issue as you describe, hoot.
Just turned it on. . . so we shall find out.
Nope. The only reason we would know is it would say it couldn't answer the question or ask for more info. "Hey Siri" did work well when actually used, and eliminates a few steps in using Siri, but the TV asked it more questions than we did. :)