I could not get the CBS All Access app (with ads) to work on my Fire TV Cube or 4K stick.  The app seems to work but after selecting the video stream, the loading circle just continues to spin and never loads. The CBS app directly on Samsung TV works fine.  

I tried the obvious, delete, reinstall, etc with no luck.  I posted on Reddit to see if anyone else had the problem and a reply said they had it with an ad blocker.  Turned off the ad blocking on eero secure and up and running again. 

Interesting issue and not sure why it allows the app on Samsung to function but stops Amazon's app.  

I hope this gets fixed.