Have you tried the channel on another Roku device?
Have you made sure the server permissions are correct?
Thank you for making these updates. My device is now showing three pieces of content in the channel. Please check your device again to see if you see the same or if you are still only seeing a blank channel. It may be that your device had not yet updated since you made these changes. Let me know if you continue to see a blank channel and we will continue to troubleshoot.
The new issue you are reporting is due to a bug that is affecting all Unpublished versions of channels. There is a team working to fix this issue. Look for the fix to come out soon and for the error to go away! Pleast note that may take a few more days for this issue to be fixed as they are still assessing the cause.
Not sure that's accurate. I have an unpublished channel that I use to test my published channel and it works fine. There must be more factors involved than it being simply an unpublished channel. Maybe it has something to do with the date a channel was submitted.