Sportsnet App / Browser - challenges with casting

Wondering if others have had success casting Sportsnet+ to their TVs. I have an Android mobile and a HiSense TV from Costco. I have confirmed that I can cast (I tried it in YouTube for example) with no issues, but when I am in the Sportsnet+ app, watching the live game, it doesn't recognize the TV as a device to pair to.

I also tried this on my Mac computer and got the message that casting was only available on "some apps".

Any tips are appreciated.