I'm at my wits end...

I bought a new Samsung QLED TV (Q80fn) and the new Samsung HW-Q80r soundbar. I connected a Roku Ultra to input 1 on the soundbar and a cable box in the input 2 on the soundbar, then ran the HDMI cable from the ARC output of the soundbar to the ARC input on the TV. The problem is that the TV does not recognize either of the input devices from the soundbar, but if I connect them to the TV directly, they are recognized and registered. I don't want to use an optical cable as that defeats the purpose of having Dolby Atmos, ehich is only available thru ARC.

Any suggestions?