Hi,
I added my Philips TV (55PUS7504) via AndroidTV integration. It works fine, I see it in Google Assistant. In Google Home app when I click on my TV I can use my phone as a remote control, but I am not able to ask Google Assistant to turn on/off or switch source. I even get confirmation that “OK. Turning Philips TV on”. Anyone knows what can be the problem?
Also it would be good somehow detect TV state (on/off).
I was trying to turn off my bedroom lamp using alexa. It respond the same as your google assistant but it didn’t turn off the lamp. After few months I realized that I renamed my lamp because when I called it to turn off lamp it just respond OK and did nothing.
Using correct name for it it work flawlessly. 
It can be something simple as using wrong name for it or maybe try renaming device to something simpler, or something else.