Hi Abay710,
I have a similar issue with a 55OLED856 fresh installed.
I connected my soundbar Samsung HW550 with the Tv's HDMI ARC. When I configure the TV to use the HDMI signal, the sound works find. But when the TV is powered off / on, there is no sound anymore. I have to double select the hdmi signal in the configuration panel to bring back the sound by the soundbar. This bug are totaly unsolvable for my wife or my childrens.
I detected an another bug with the HDMI ARC, when the sound is set to the minimun 0, and next to 1 or more, there is no sound anymore. I have to double select the hdmi signal in the configuration panel to bring back the sound by the soundbar.
I think that all of this bugs are software based. Completely unacceptable for this kind of well known protocol. At time, there is no possible new update detected by the TV.
I would like to bypass these issues by using the optical audio output, but in this scenario I can't manage the soundbar with the TV' remote control.
Regards
Topdam