[post moved to appropriate board]
Thanks for letting us know about the issue that you are experiencing.
After removing the channel from the Roku home screen by navigating to the channel tile, pressing the * key on your remote and choosing 'Remove channel', make sure you restart your device from Settings>System>System restart. Once your player starts up again, add the channel back once more. Does this clear up the issue you are seeing?
Can someone from ROKU please respond to this thread and at least acknowledge that this is an issue with all 4K TVs + Netflix and you guys are working on this. There has been no response since last Monday.