Thanks for posting to the Xfinity Forums. Sorry for the issues you're having. I'd be more than happy to investigate this for you. First, I wanted to verify the type of cable box you're using. By chance do you have an RNG150 box? If so, you will need to upgrade your box as that box is no longer compatible with the Music Choice channels.
If you are not using an RNG150 box, have you tried to perform a system refresh?
Performing a System Refresh on X1