HI all. I'm new to the forums but I've been browsing for a bit. I had the same issues that others had with this soundbar when paired with an Xbox One S where I was unable to select Dolby Atmos in the Xbox settings. For reference, my tv is the 55 inch C7P. I was recently prompted to update the soundbar (on 8.7.17 to be exact) but that did not fix the issue. Yesterday I decided to unplug the cables, then re-plugged them in but before turning on the tv, xbox and soundbar, I went into the Music Flow app and under settings, speaker, I "initialized" the setup and selected the bottom selection which was hdmi rather than optical and then hit complete. Once I turned on my devices, I was surprised to see that the xbox finally let me select dolby atmos. After that, I fired up the Dolby Access app but then that had some issues too. At first it would play the sounds but then it would cut off. I closed/quit the app and after a few tries and even restarting my xbox, I got the app to work and the soundbar played the sound and also displayed "Dolby Atmos" on the LCD.
Anyway, I don't know if what happened to my setup was just pure luck but I hope this can possibly help others who have the same issues.