Strange Thing With LG PLex App

[HipKat]

I have Plex on my Hopper 3, Firestick and my 4 yr old LG TV App. My LG Optical output is PCM only. I have no idea why, but regardless, it's why I normally run optical out on the hopper with my Polk 5.1 SS System. When the output is PCM/Stereo, the power light is white. When it's Dolby Digital, it turns green. For the Firestick of Plex, I have to move the optical chord out of the Hopper and plug it into the TV.

Last night I was streaming Godzilla: King of Monsters with the Plex LG App - optical in the TV - and whoa!! Dolby Digital!! The light turned Green. How was this possible?