HomeCinema sound bar with Marantz NR1200?

We needed sound for a projector in a new home theater room. I got the NR1200, and the Denon HEOS HomeCinema soundbar.

I had thought — given both advertise HEOS compatibility — that there would be some direct wireless receiver connection to the soundbar. There apparently isn't, meaning it all has to be effected through the HEOS app. 

But now that it's set up in the HEOS app, there's no way to switch between inputs without the HEOS app.

E.g., if I'm using the gaming input (HDMI from a PC) and switch to the AppleTV input using the NR1200 remote, the audio does not switch. When I then go to switch it in the HEOS app, I'm told 

To play the AV input source in "Home Theater + HEOS HomeCinema" it is necessary to set the "MAIN ZONE" to the same input source. Do you want to switch the "MAIN ZONE" to the selected input source?

If I make the switch in the app, the sound follows automatically. 

Customer support had no answer. Is there really no way to make the remote as "smart" as the app? Do I really have to supply a smartphone to use my soundbar speaker?