Does the issue only occur on a specific channel/content or across other channels installed on your Roku device?
If you haven't tried yet, you can remove the affected channel then re-install it. To ensure the process is successful, make sure to restart your device before adding the channel back in. We would recommend doing this from the Settings menu by navigating to Settings > System > System restart > Restart.
Re: Roku on Samsung smart tv freezing picture while watching
We’re having the same issue. Roku ultra on Samsung TV. freezing picture but sound keeps going. It’s happening on different apps when streaming live. We replaced the Roku, HDMI cabling, restarted, installed reinstalled apps. its only happening on one TV. the samsung.