Please try removing the channel, restarting your device from Settings>system>System restart. Once your device loads up again, add the channel back again from 'Streaming channels'. Then, visit Settings>System>System update>Check now and perform a system update. This should resolve the issue.
If not, please follow up with the channel provider's support team to report the issue you are seeing and request additional assistance if other channels on your device are still working normally. You can reach Spotify support here: https://support.spotify.com/us/
Roku Community Manager