Thanks for the quick feedback. I deselected DTS and set channels to 2.0 and 2.1. Neither 2.0 nor 2.1 sent 5-channel audio to my TV.
I send my TV audio to my AVR over an HDMI (ARC) cable. When I select “Antenna TV” as the input on the TV, I get 5.1 sound at the AVR. My RPi is connected to the TV via an HDMI cable (not ARC).
Thanks again for any help,