What Roku model device are you using? Is this happening on a specific channel, or is this occurring with all channels? Have you tried another HDMI port on your TV as well as switching out the HDMI cable used to connect your device?
Nothing but B&W images on all Roku input like Netflix. My streaming device is old, ca. 2013. It's a model 2720X, ser no. 1RG48S021444. Is there an equivalent newer unit I can order to replace it? Cabling, etc., seems okay.