Missing channels

We have the Xfinity X1 service but are trying to switch from using cable boxes to using the Xfinity stream app on our tVs that are capable of it. We have a TV that has an Apple TV box and we installed the Xfinity stream app. However, many many channels are missing including some of our favorites like TLC. When I pull up the Xfinity stream app on my iPhone, however all of our channels are there. How do I get all of the channels on our Apple TV box I’ve tried signing in signing out but it didn’t help.