Atmos not working. I have a JBL 9.1 and plugging the Roku directly to the Atmos soundbar. Atmos playback is not detected or working in any app. Netflix, Prime Video, and Disney +.
Atmos does work with another streaming stick from a competitor.
NetFlix Atmos is only supported in the recent 4800 (2020 Ultra).
For general Atmos support otherwise, check that:
Settings/Audio/HDMI= "Auto-detect" (highlight Auto-detect: if DD+ support isnt indicated you wont get Atmos passthrough)
Settings/Audio/Audio mode="Auto (DD+ etc)" (if this isnt on auto with DD+ indicated, you wont get Atmos passthrough)
"Volume modes" are off/disabled (press options (*) during playback, disable/turn off all/any volume modes as these will disable multichannel output)