@rocknerd-
Re screen flashing black - does this happen when starting/ending programs and when going in/out/between commercials? If so:
Under "Settings > System > Advanced system Settings > Advanced display settings" some Roku devices have an "Auto-adjust display refresh rate" item. If this is enabled, the Roku circuitry sends the signal output at the refresh rate used by the original source material, commonly 24 fps (frames per second), 25 fps, 30 fps, 50 fps, or 60 fps. Every time the source refresh rate changes, the TV must adjust its display to accommodate the new rate, which on many sets results in a short blackout.
This can happen when starting/stopping new programs, and when going in/out of commercial breaks that have a different native refresh rate than the programs they are inserted into.
If "Auto-adjust display refresh rate" is set OFF, the Roku sends everything with a rate of 60 fps and the TV doesn't have to adjust on the fly.
The tradeoff here is that, depending on your set, movement of things on the screen for non-60 fps sources may not be as smooth without a refresh rate adjustment. You have to decide whether this change is worth it to you.
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Ultra 4800 | Streaming Stick 4K+ 3821 | TCL Roku TV 43S245/C107X