I am in the same boat as the original poster, streaming multichannel audio from my PLEX server to other non-PC equipped rooms in my hours (such as my home theater). PLEX used to play by my surround audio files just fine. After testing that this worked, I spent many days/weeks archiving my surround music catalogue into a digital format to stream to other rooms in my house using PLEX. Then I updated to the most recent version of the PLEX server this summer, and after that I found, as mentioned by the original poster, the playback was just the front 2 channels. So after a bunch of trouble-shooting and rigmarole, I found that if I reverted to a previous version of the PLEX server ( 1.15.2.793 from March of 2019 is the version that I settled on), playback of multichannel audio was just fine. And I’ve been happy ever since. That is until today, when I got an email letting me know that starting soon, devices will require at least version 1.18 of the PLEX server.
So PLEX absolutely used to have it the ability to play multichannel music files, and now they have phased it out. I do not understand it.
