I have a home theater system that includes a Dolby Atmos enabled Onkyo receiver and a 5.1 surround setup. I configured audio similar to what you describe (Auto audio format, Passthrough) and never see Atmos show up when I press the surround format button on the AVR remote. BUT if I change the format setting to Dolby, I ONLY see Atmos which sucks. Does unplugging and restarting it make a difference and if so, why? I'll add that I love the Tubi catalog but for unknown reasons they do not stream in native audio formats. Thanks
Sorry for the additional response but the site won't allow editing. Wanted to let you know I unplugged/re-plugged the HDMI from the Roku and power cycled. When viewing the audio settings it shows Atmos, DD+ available but when streaming a Netflix title, Atmos is nowhere to be found. If I change to Auto rather than passthrough, Atmos becomes the PRIMARY surround format, which sucks. Any ideas what's going on here? Seems weird the Roku detects Atmos but won't make it available with passthrough.