I have a Sonos Arc connected to my LG B7 (ARC), and an Apple TV 4K, if I play an EAC3 file (DD+) on the Apple TV, the Arc starts playing back in DD. But if I play the same file on the Plex WebOS version, it plays back in DD+.
I have no idea what is causing this issue, but I am assuming that it is the Apple TV. As the LG Plex version can play back DD+ over arc to my Sonos Arc with no issues. I can play DD+ (Atmos) fine on Netflix on the Apple TV, it is just using Plex on EAC3 files that do not playback in DD+. I have checked and everything is working via Direct Play, but have no idea how to fix this issue.