Missing 4 channel / ambisonic audio export setting

WOW! Ive seriously been going insane trying to figure out what I was doing wrong when before it was pretty straightforward and Premiere even did a pretty good job auto detecting various clips with ambisonic/binaural audio.... I even tried exporting raw audio data back through ambisonic player in every possible export setting...
Still... no worky... 
I'm relieved to know there is a glitch but pretty frustrated almost angered I wasted so much time trying to get my hear straight.  
What do we gotta do? Instal old version??  This is a REALLY BIG deal!

I wanted to also report & confirm that the option to select a 4-channel output from Adobe Premiere / Media Encoder means that any Ambisonic Tracks are being output as mono tracks. I was disappointed to see that the update yesterday did not fix this. And reverting back to the previous version of Adobe Premiere 2020 / Adobe Premiere 14.9 not only also didn't work, but it also mean that I had to recreate the sequence I wanted to export because you can't save an Adobe Premiere 2021 project and open it up in Adobe Premiere 2020. I tried Final Cut Pro XML export, but even that didn't fully work as it's buggy and not well supported.

I did however find a workaround in combining the externally-produced ambisonic file back into my exported 360 video via ffmpeg. This took a lot of trial and error since it's hard to monitor ambisonic audio locally, and YouTube takes a long time to process these file. Here are the commands that worked for me. I'm sure there's ways to consolidate these commands, but I've found that it was easier to break it up into component parts when you're doing a 3-4 step process that isn't working and takes a long time to debug and isolate what part of your command isn't working. I find the channel mappings to be the most confusing part.

Remove the audio track from exported video to make channel mappings a bit more intuitive:
$ ffmpeg -i Exported-360-Video.mp4 -c copy -an Exported-Video-with-no-audio.mp4

Convert the Ambisonic *.wav file into a *.aac file:
$ ffmpeg -i Ambisonic-Input-File.wav -acodec aac Ambisonic-Input-File.aac

Add all of the 4-channels of Ambisonic Audio back onto the video.
$ ffmpeg -i Exported-Video-with-no-audio.mp4 -i Ambisonic-Input-File.aac -c copy -map 0:v:0 -map 1:a:0 Exported-360-Video-with-Ambisonic-Audio.mp4

Be sure to use Google's Spatial Media Injector to enter in the right metadata if you're uploading an ambisonic-enabled video file to YouTube. Hopefully Adobe will fix this bug so that folks won't have to mess with ffmpeg on the command line just to be able to upload an ambisonic-enabled video.

Hi Simon James Gray,

We're sorry about the poor experience. In the latest release only mono, stereo & 5.1 channels are available for Ambisonics audio. We're currently investigating this issue. For the time being, you may use Premiere Pro 2020 for 4 channel Ambisonic audio support.

Thanks,

Sumeet