Xfinity Stream App not Casting to VIZIO TV with built in Chromecast

I have been streaming live TV to my Vizio TV for months. 

Last night, I tried to cast. It connects, and if I'm fast enough will connect the show I want to watch, but after 25 seconds, it disconnects and returns to the home screen.

I have power cycled my phone, modem, router, and my TV, and even factory reset my TV. I have also searched a lot of the forums, but ultimately nothing works. 

Other apps cast to my TV without issues, so it is not my phone or the TV but appears to be the xfinity stream app.

What is the solution for this?