This seems to be correct but as @dan.reynolds has mentioned these are just eight audio channels using the standard Windows API speaker assignment. The cool thing is you can record these directly to a WAV file with eight channels. In fact my Motherboard has 7.1 that I can activate without having speakers. If you don’t have an audio card (most modern MB support 7.1 audio) you can use another technique with a small driver/app called ‘Virtual Audio Cable’ and assign eight virtual channels that Unreal will recognize as a Windows audio 7.1 audio device because ‘Virtual Audio Cable’ is also using the Windows Audio API labeling convention. Sadly I was hoping to fool Unreal into believing that if I created 12 virtual audio output channels it would recognize it as 7.1.4 for height channel speaker placement allowing for Dolby Atmos like experience. Sadly, Windows 10 API does not support more than eight channels and not sure if Unreal recognizes channel assignment if you have a Dolby Atmos receiver installed for 5.1.4 or 7.1.2 or 7.1.4 and not willing to spend a $1000 to find out at this moment if it does. If Dan or anyone at Unreal can confirm that height channels exist if you have a Dolby Atmos receiver hooked up that would be great since I am now having to create two passes in Sequence to derive height information. I do this by rotating the camera 90 degree (roll axis) and mapping these speakers ± height positions into my AmbiX encoder. So I am really working with six channels X/Z (azimuth) and six channels Y (elevation), plus two channels for 0/0/0 axis for center/OMNI and LRE (with low pass filter applied). I do this because I don’t want to have recreate my soundfield twice when I create stereo 360 videos for YouTube/Facebook. It works great except for the slight timing issue in having to create two passes that I have to manually line up in Adobe Premiere or DAW (Reaper). If it is confirmed that Unreal will produce height channels in the WAV file, I will purchased a AV receiver just for capability to produce a discrete channels of the 3D audio field. Ultimately I would love someone who has better knowledge of audio API and C++ to create Ambisonic 2nd order WAV file.
Update: I purchased a refurbished LG SN7R 5.1.2 Channel Soundbar with Dolby Atmos to test the possibility of Unreal sending out proper channel assignment. If it works, I will at least have two L/R height channels in the WAV out file.
Update 2/22: Received LG SN7R and I am now able to see Dolby Atmos and I do render 8 channels in the WAV file, but sadly the files appear as standard 7.1 audio tracks, instead of two height channels. I compared this to standard 7.1 output WAV file with the same track outputs. So it appears Unreal cannot recognize when a Dolby Atmos HDMI device is selected other than as a standard 7.1 surround channels.