Have you tried, as the previous user noted, to go direct HDMI to TV.
Then, if TV has an optical out, go from TV to soundbar?
Should work the other way, but this may be a sutiable workaround.
I have a Samsung soundbar and hooked it up this way because soundbar only has 1 HDMI input. So to get sound on all devices connected to TV, I had to do it that way.