Sounds like you are just seeing the image placeholders so images are not downloading from the server.
Try restarting both your Roku device and your router. Occasionally happens to me when my internet speeds drop. Other than the images not loading, the channels still operate fine, just may take a little longer to load.
Usually a reboot of the equipment will resolve the issue.
Roku Community Streaming Expert Just another Roku user... I am not a Roku employee. Insignia RokuTV, Ultra 4660, Premiere+ 3921, Express 4k+ 3941, Streambar 9102