Just an update on the issue with my 2014 P702ui-B3 (P series tv)...
I've directly connected my 4th Gen Apple TV to my Vizio and I can turn the tv on, adjust the sound, however it will not turn it off.
I've seen other users on Macrumors with different Vizio Models such as the M where this works but as of yet not a single P series owner has reported that it works.
Vizio's Twitter support practically states it should work:
https://twitter.com/VIZIOsupport/status/662645032898416640
And with a DM I was sent they said it should work with the P series but that's all they said as if they didn't care if it didn't work for me.
Apple's own documentation states this should work:
https://support.apple.com/en-us/HT205225
What irks me is after cutting the cord so to speak my tv was on non stop for weeks before I noticed it wasn't fully turning off as I now have the power on indicator light turned on and verify this. For weeks it appeared to be off except for a brief flash at the top of the screen with info like wifi. Thought it was a glitch.
Also calling Vizio yesterday was very hit or miss. I had a very knowledgable rep from South Dakota and I accidentally hung up on him.
The next two people were from Missouri and they told me Vizio support on Twitter was wrong and that Vizio doesn't support turning a TV off via CEC. They told me it wasn't an advertised feature and even went into detail about how my PS4 or Apple TV may be sending the wrong IR signals. For starters the PS4 doesn't even have IR and secondly CEC is via HDMI cable and not wireless. I regretfully spend a combined hour with those two reps and each call ended with them telling me they'd note my account and maybe an engineer would see it and then maybe someone would take action.
Irritated I called one final time and again got someone in South Dakota who said the previous reps noted the wrong stuff in my Case and that they were saying I was trying to turn the tv off with a universal remote. She said she spoke to tech support and that they confirmed the P didn't support turning off via CEC and that the tech whom I was never allowed to speak with "Might" pass this along to their engineers.
In summary every model but the P seems to work and everyone BUT customer service indicates this should work (Apple, Vizio Social support).
It's a first world problem that's already cost me a lot with energy bills and the lack of actual support and disregard makes me very unhappy. First world issues or not this is one of the most expensive piece of electronics I have and it shouldn't be this hard to have an issue acknowledged.