Casting Issue with Xfinity Stream App on Google TV

Dear Xfinity Support Team,

I am writing to report a technical issue with the Xfinity Stream app.

I can successfully cast apps like YouTube from my mobile phone to my TV, but I am unable to cast from the Xfinity Stream app to my new TCL Google TV. When I try to cast with the Stream App I don't see the TV.  I can see my Google Nest Hub, but not the TV.  Ideally I would like the app to be directly available on the TV, but I understand that is currently not an option.  I wish I knew that before I bought this TV....  

Could you please assist me in troubleshooting this issue?

Thank you,

Matt