Is this within a particular channel app (which one?) or for all channels on the Roku?
These things are just special purpose computers. Like their big brothers sometimes clearing things out by restarting them can correct problems. (For Roku TV users reading this: if you have "Fast TV start" enabled, turning the TV off and back on just puts it into and out of a standby state and does NOT give you a complete restart.)
You'll find the "System restart" option under "Settings > System > Power" for Roku TVs and some Roku streamer models. On models without a Power option, it's under "Settings > System".
If a restart doesn't do it, or if you don't have sufficient control with the remote to navigate the Roku menus, you can also restart by pulling the power plug to the Roku for a few seconds then plugging it back in and waiting for it to restart.
Roku Community Streaming Expert
I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well.
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Ultra 4850 | Ultra 4800 | Streaming Stick 4K+ 3821 | TCL Roku TV 43S245/C107X
