The problem seems limited to certain Pixel models, as other models and other Android phones play EAC3 audio OK.
@BigWheel mentions earlier in the thread that the Plex Transcoder upgrade is a prerequisite.
The upgrade is currently a Forum Preview (pre-alpha): Transcoder Upgrade Forum Preview.
No info/dates/etc. are available for the transcoder update moving to beta/public status, the mobile apps getting an update, etc.
