I just downloaded the beta version of the app via the stable app for my Fire TV Cube and the icon is missing. I just get a generic black square on the screen. It's also pretty hard to see.
I thought maybe it was just the one device I have downstairs so I did the same on the one in the bedroom and I get the same thing - no app icon.
The app opens and runs just fine. I tried deleting it and re-downloading it but same thing happens.