How to choose transcode audio targets (Audio transcoding to Opus rather than AC3)

Plex Players
31

My setup only supports DDP and DD, so when it was transcoding to EAC3 over HDMI everything was fine, but now on OPUS, I get same audio from all speakers, same is the case with DTS, it copies the same audio feed instead of transcoding( this was the problem even before OPUS change was made). I am not sure how to get EAC3 over HDMI in case the audio codec is not supported as there is no option for selecting the preferred transcoding in HDMI. I never get 5.1 audio over PCM but stereo