Hey guys
Just updating on this situation.
I was experiencing this with the tcl e19us but returned it because it sucks.
The hisense 55R7 seems phenomenal but the same thing is happening.
Google commands will turn the TV on through the Chromecast, but not turn it off (gen 1 and ultra).
Whereas on my 4 year old sony bravia kdl it does (gen 1 and ultra).
I tried all Google's troubleshooting and various threads I've found and then tweeted out to google for support.
See pic
Chromecast problem https://imgur.com/gallery/wqBFBqt
Long story short they say they are investigating it.
Weird that my Sony TV still turns off but this won't.
It also says my TV has google assistant ready, but support team knew nothing of that and are investigating, seems like it's an error in the spec sheet.
Careful of your screenshots on the www. That screenshot of your Hisense account shows your email address, and it's there on Twitter for all to see