Try removing the channel from the Roku home screen by navigating to the channel tile, pressing the * key on your remote and choosing 'Remove channel'. Then restart your device from Settings>System>System restart. Once your player starts up again, add the channel back once more, specifically in that order. Does this clear up the issue you are seeing?
If you are still experiencing an issue with just that channel and on multiple devices, you'll want to contact the channel provider support directly to inquire further. Many channels on Roku are developed and maintained by the channel provider themselves.
I am also unable to reload the weather channel on my TCL Roku tv after having it load initially. The app gets hung up on the screen “standby, changes in the forecast “ and never completes loading. System reset does not help.