I've started having issues with transcoded audio on Plex. First noticed it when transcoding from TrueHD files to EAC3 5.1. It also happens transcoding from 7.1 AAC to EAC 5.1. The audio will jump ~6-8db, but it seems like it only happens on one or two channels, so the L/R channels, but not the center. It's most noticeable in action scenes, or scenes where the score has a consistent orchestral part, you can hear the constant string section dropping out or jumping back in several times in a few seconds. The audio is not stuttering or missing parts, its just the volume is not consistent. I've also noticed the overall volume is lower than it should be; on files where I can direct play a 5.1 track from inside the container, the volume is much louder overall than the transcoded audio.
I am running the official Plex docker on Unraid 6.9.2, the client is Plex on Roku on my TLC TV, HDMI ARC to a Yamaha TSR-700 with 5.1 speakers, set to straight.
I've tried toggling Normalize Multi-Channel audio, changing the transcode from high speed to high quality, and deleting the codecs folder in appdata. On the client, I've tried toggling the AAC Stutter Workaround and trying various direct-play and direct-stream options.
Any suggestions?