What's your status? I have a 4660 to an Onkyo receiver and the Roku Audio shows all the audio options. I also have a 4802 connected to an Integra receiver and Roku's settings for Audio don't show me any Digital choices like the 4660 does. So, on Netflix and Peacock, on the 4802, everything defaults to "Stereo". I have all Sound options Off, and have restarted it many times. It's driving me crazy! Why is this?
How do you have audio settings configured? Best practice is using pass through and automatic format detection. While my Onkyo supports Atmos, I rarely if ever experience it being used. Depending upon the source, most content streams in Dolby Surround though its easy to select other formats with the Onkyo remote. That said, if I choose custom rather than pass through, Atmos appears in the format choices which when you think about it is weird. I've yet to figure out how Roku engineered the audio settings, but it is what it is