XBOX One X Atmos passthrough

[zeustek 1]

I'm hoping someone can share some insight. I just upgraded my AVR to a Yamaha RX-A8A which supports Atmos and DTS-X. I have an 86" LG TV which does not appear to support Dolby True HD or DTS-X so it will not pass these to my AVR through eARC. I also tested a Google TV device a friend gave me, and a Chromecast Ultra and after testing and searching online I discovered that these devices also don't support the higher bit rate audio codecs.

I bought an XBOX one X a while back for Atmos support but it had compatibility issues with my previous AVR, I figured this was my last ditch attempt to get the full Atmos experience. It needed some updates but I enabled Atmos and my AVR reports the input as PCM. I thought this was a little strange so I loaded up the Dolby app and played the BS demo videos and my AVR reports the input as "Atmos/PCM". No kidding. I checked the AVR's info pages and it shows the audio channels as "---". I also tried the XBOX test pattern and it plays all 7.2.4 channels. I enabled passthrough for my AVR and figured I was GTG.

I loaded up emby and found a couple of films with Atmos. One of them previously worked on my old AVR using a Windows PC with passthrough enabled in the EMBY theater app (Mad Max: Fury Road) (the PC is gone, so this isn't an option right now). The audio showed as Dolby True HD in Emby and my old AVR decoded the extra Atmos information and reported "Atmos" on the display. The second film is reported in Emby as "Dolby True HD(Atmos)" and also has DTS-X. However, when playing back both of these films on my XBOX using Dolby I either get no audio (if I disable audio transcoding on the server) or I get a 5.1 AC3 transcode. DTS-X on the other hand is passed through to the AVR no problem.

Is this just a shitty implementation of Atmos on the XBOX? Or have I done something wrong?