you can read the prior post in threads, Eugene really did try. I wanted only plex as i have no other way to play atmos to my receiver as my one year old LG B6T wont passthrough the damn atmos.. for now stuck with plex addon
Eugene undoubtly did a great job (thanks again!!).
I am not sure, but I think I read some time that OpenPHT is based on Kodi 15. So maybe that is the reason why there are no HD audio formats with OpenPHT? But that is just a guess from an amateur like me
So I share your fate: stuck with plex addon.