Are you checking the SmartCast app? it should tell you what format is playing. I think if you're seeing the green light and the speakers are moving you're getting Atmos. Unsure how the Vizio Tv's work but when you use eARC on the LG OLEDs it no longer tells you audio type of the tv screen, while the internal speakers will say "Dolby Atmos" in a popup.I have the Vizio OLED and had the Elevate for a few weeks. I had the same situation where the TV would only say Stereo and never Atmos. Does the same thing with my Sonos Arc as well. I think it is just a weird quirk with the TV because like you said I got the green light and upfiring speakers when I had the elevate and I currently have a Dolby Atmos badge when I open the Sonos app. Would be nice for Vizio to fix this to confirm for us that we are getting Atmos but at this point I am pretty sure we are.