M$ changed TV Guide providers from Zap2It to Rovi effective on July 7, 2015. As I understand it, this affects Xbox and Media Center users or users just using their guide service like myself.
M$ ought to just own up to this as at least part of the troubles they are experiencing. Instead, the public gets a version of it fluffed up by M$ marketing. Personally, I think that I am going to switch away from using their EPG service as it is often problematic. This time, it is majorly screwed up for many users.
You can read about the change here -
http://www.thegreenbutton.tv/forums/viewtopic.php?f=5&t=8903 and/or post your complaints about the guide here -
https://connect.microsoft.com/site1145/Feedback