No sound on S/PDIF ASUS Xonar DG

Hello, I have no in-game sound (except sound of intro), I’m using ASUS Xonar DG and my receiver connected via optical S/PDIF cable.
In every other application works great, but not this special one (Horizon 4).
In Sound options, there’s no any options to turn on/off audio enhancements.
I’m running latest Win10 (v1803) and game version, latest video drivers (416.81), latest UNi Xonar drivers (1.81a-r2).
By the way, when I’m changing audio output to my display’s speakers (connected via HDMI) everything is working, but as you can understand, I wish to play in full audio.
Any ideas?