I have confirmed from different sources, like ratings.com review of the 55EG9100 LG OLED, that they could pass DD from HDMI input to optical output on this TV.
I also tried hooking up my PC which has an AMD R5 video card with HDMI audio out. When I try to configure the audio on the card the AMD software only gives me the option of 2 channel, which tells me that the TV is telling the HDMI devices that it only supports PCM. I have been through all of the setting on the TV and still haven't been able to get this to work for me. Stumped at this point
. I am waiting to see if anyone on the AVS LG OLED forum might have some suggestions.