I have some more information on this problem which started yesterday. I have always had the brightness setting on my TV set to "Normal", but the night before last I was streaming a movie on Amazon Prime which had rather dim video, so I increased the brightness up to "Brighter". I left the brightness at that level. Today I realized that the brightness level was still at "Brighter" so I reset it back to "Normal" and, lo and behold, the problem went away. This is clearly a bug with the TV. The problem symptom is that the screen sometimes goes blank when the input video switches from the program to a commercial or from one commercial to another; the display comes back after recycling the TV's power. The TV must be either losing sync and not recovering or, perhaps when a bright commercial suddenly comes on, the TV's video circuitry shuts itself down because it thinks it's being over-driven. As an electrical engineer with a lot of experience designing and troubleshooting video display systems, I think these are the most likely causes. In any event, this is something that Roku should be able to fix with a firmware update. This is happening on a 65 inch Roku Plus TV made by Roku, not TCL, Hisense or anyone else, so Roku owns the problem. This video blanking should not happen regardless of the TV's brightness setting.
