We would like to know how to identify and resolve any playback issues. I have a few questions to better understand the behavior you are seeing:
When did this issue first start occurring?
What Roku model device are you using?
Have you tried removing the channel, restarting your device from Settings>System>Power>System restart (If you do not see a Power submenu, skip to the next step), then once it loads up again, adding the channel back once more to see if that clears things up?
With more detailed information, we will be able to assist you further.