Thanks for posting here in the Community!
In some cases, removing the affected channel and then reinstalling it helps. To ensure the process is successful, restart your device before adding the channel back in. We would recommend doing this from the Settings menu by navigating to Settings > System > Power (If you do not see a Power submenu, skip to the next step.) > System restart.
For detailed instructions, refer to this Support link: How do I resolve channel playback issues?
Let us know how it goes.
All the best,
Roku Forum Moderator