About half the time after selecting channel, picture comes up extremely zoomed, only seeing the top left quarter of the picture. My fix has been to turn off tv using roku remote and then turning tv back on. Using Streaming Stick 4k and Vizio D series.
Does the issue only occur on one channel or regardless of the channel you access on your Roku device? If you haven't tried yet, connect your Roku to a different HDMI port at the back of your TV, or try using a different HDMI cable.