To bypass the sound dropping out issue (detailed in another thread), I plugged the roku directly into the Vizio soundbar. Now I have a new problem with video. If I turn on the tv, the roku will alternate between 720p and 1080p and display flicking. The screen will have static and jump between resolution or to a blank screen and back. Sometimes, it stabilizes into a 1080p picture and everything is fine. Most of the time, the jumping between resolution does not go away. The flickering is often accompanied by loud popping noise. If I unplug the roku and plug it back, the roku reboots and then works properly. and continues to work until you turn off the tv.
I notice that the home screen starts out in 720p and then adjust to 1080p. I tried modifying the display setting to auto, 1080p, and then 720p. What I have notice is that the issue goes away when I select 720p. In auto or 1080p, the display goes back and forth between 720p and 1080p.
I switch off ARC, but it does not resolve the issue.