Please accept our apologies for any inconvenience this has caused.
Have you restarted your Roku device before adding the channel back in? If not, we suggest trying it once again. That step is crucial when performing the troubleshooting.
Visit this Support link for detailed instructions: How do I resolve channel playback issues?
Moreover, if after attempting the suggestions above, you are still unable to play videos from one channel while videos from other channels play fine, contact the channel provider's customer support team to report the issue and get help. Channels on Roku are maintained by the channel developer themselves.
You can reach out to Hulu Support here: https://help.hulu.com/s/?language=en_US
All the best,
Roku Forum Moderator