Same problem. LG C1. When I turn the TV on, the Roku screen is frozen. I have to turn the tv off (using Roku remote) and then back on for it to work. This happens every single time I go to watch TV.
You didn't mention what Roku model you're using. Sometimes this makes a difference in responder's ability to give targeted help.
If your Roku has a "Settings > System > Power > Auto power savings > After 20 minutes of no interaction" setting, try disabling it.
More info on this setting: https://support.roku.com/article/6306527767575
