Ok, short back story. Bought two Roku Ultra's approx 1 year ago. At the same time, purchased a 55" Vizio Home Theater Display w/built-in Chromecast/Apps Smart TV. Never registered or used the Chromecast features on the TV.
The Roku Ultra and Vizio TV have been working flawlessly that entire time, approx. 1 year. About 4 days ago, while streaming on the Roku, intermittently it started black screening. It would not resume transmitting audio/video to the TV unless I unplugged and rebooted the Roku via the power source, or by simply unplugging the HDMI cable and plugging it back in. I then tried streaming via apps on my Sony BluRay player to see if it was the TV. Worked fine for two movies. Then, I simply switched the HDMI cables from the BluRay that is working to the Roku Ultra. Worked fine for about 10 minutes, then black screened again. I then brought in another Roku Ultra from a different TV and it worked fine for about 3 mins, then black screen. I read online for hours, trying various suggestions from flipping my HDMI cables over, to doing a soft reset on one of the Roku Ultras....still, getting black screen after a bit.
I then took an old Roku 3 from my bedroom, put it on my Vizo TV that was having the issues...been working flawlessly for 3 days. And, the Roku Ultra's that were black screening on my newer Vizio 55" work perfectly (so far) on my Sony in the kitchen and older Vizio 47" in my bedroom.
Has anyone even heard of such an issue? It sounds like an issue with the HDMI "handshake," but I tried multiple different HDMI cables, multiple different Roku Ultras, flipped cables...plus, it's been working perfect for a year on the same HDMI ports and same cables. Could either Vizo or Roku have done an "update" I'm unaware of that could have caused this?
Have you looked at or attempted to change any HDMI settings on the VIZIO, such as turning off the CEC option? I had a devil of a time with an early HDMI TV that was only resolved sadly, after disabling CEC.