Samsungs have a well known issue of not passing beyond stereo and may not downsample to stereo to pass out over ARC.
So right off the bat my view is it's not going to work.
But since OPTICAL WORKS, you are have made it farther than most.
This is why, over and over folk tell you to forget that setup and go with a receiver.
Hoping you guys can help me out, as support from both Samsung and Sony blames the other. REALLY hoping I can get ARC working.
• Sony HTST9 – Sound bar
• Samsung 2015 un55ju7100
• ARC from TV connected to ARC on sound bar, using HDMI
• HDMI Arc is plugged into soundbar, all other HDMIs are being plugged into the rest of the TVs HDMI slots.
• ARC enabled on sounbar
When I try enabling ARC on my TV through the speaker list by selecting HDMI, I’m being told that there are not Anynet+ devices.
I tried using optical out, connecting from the soundbar to my TV and everything works fine. Changing the inputs on the TV from AppleTV to Cable box, everything works great and I get sound. I can even change the volume of my soundbar using my TV remove, which is great. But I would really love to get HDMI audio working, instead of just Optical.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic