I am having a similar issue, and noticed this with Food Network. This just started on 4/15/19. I have contacted Xfinity numerous times in the past 24 hours about this. I am no longer able to stream content on the app on my Roku, mobile device, or even access network content directly on the website with my Xfinity login. It now tells me that my "Xfinity subscription does not include this content" when it actually does. I have not had anyone from Xfinity be able to resolve this issue or even have the courtesy to call back when they say they will.
Has anyone has this issue with their xfinity login on third party/network apps/streaming before and successfully had it resolved? If so, please let us know how you did this!