The only time I've ever experienced this, several months ago, all it needed was to restart the Roku. Settings > System > System restart, or if you can't get enough control to do that, just pull the power cord for a few seconds.
- Roku Streaming Stick +, 3810X, Ser YH0059427035, wifi - Samsung UN55ES6100
- Roku Streaming Stick, 3600X, Ser 5S56D8240827, wifi - JVC EM37T
- TCL Roku TV 43S425/C107X, Ser X000001R60KV, wifi