5.1 Audio totally wrong on ATV music (TV and Videos OK)

Server Version#: 1.17.0.1709 (FreeNAS)
Player Version#: ATV latest

So I have the ATV setup to convert audio to 5.1 (NOT auto) and that is connected to my receiver (Logitech z-5500) by optical.

I see that if I play a .AC3 audio file, my receiver does not see it as 5.1 and it comes out on screwed up channels.

If I use ffmpeg to put that audio on any video track (x264 using .mkv) and play it as a video, it comes out perfectly (5.1, correct channels).

I saw that six months ago there was a complaint about flac and 5.1 on ATV but it was closed (3 month idle) before reporting it as fixed. Is it possible that the same problem exists with .AC3?

Note: I see that it is leaving PMS direct play so it looks like PMS is off the hook. I strongly suspect the Plex client on ATV.

Anyone see this?

There’s this really long thread that may be applicable to what you’re experiencing:

There has been no fix and it involves all audio multi channel formats. You found the same workaround as some other people have, changing the format to a video format. That is the only solution right now. I’ve just got too many files to do that. This have been going on for over 7 months now. Come join our thread (the one that the Plex Moderator pointed you to).

I apologise. I did search before posting but I saw a similar thread focusing on FLAC and somehow missed this. I’m very embarrassed and apologetic! I will see you on that thread.