Server Version#: 1.15.6.1079
Player Version#:7.16.1.10610 Plex for Android
My TV is connected with Samsung home theatre 5.1 over ARC HDMI. I have tried to play AAC 5.1 test MP4 and one surround channel played in subwoofer, the second one was silent and subwoofer sound played in one of the surround channels.
If I use the same file with Plex Player for Windows 10 with the same TV, home theatre and settings, everything is all right. So I guess that the problem is in the Plex for Android App which is installed on the TV.
I have tried to use passthrough HDMI audio but the result was the same.