No full screen on live TV with streaming app

What's up Comcast? Why suddenly did full screen disappear on live TV only with the Xfinity Stream app? Every other app I use is full screen... even your movies and the search enables full screen... but not LIVE TV... I have 4 big black bars to be frustrated about.

One of your agents suggested I upgrade my Roku, so I did, and that did not fix it. One day I had full screen, and the next it was gone.

I've been reading this is a common problem with your app.