The problem with reatek in particular with the optical output, do you know the reasons?

Question

Realtek

Good hour. Faced such a problem. installed win10, everything got up and the sound works, but only on 2 channels. my task was to connect to the receiver via optics, which I did. The problem is that in the settings I can’t install sound 5.1, this tab simply doesn’t exist, I installed the latest driver 6.0.1.8036, however, even the earlier ones did not change the situation. I can't figure out what's wrong? before, when win7 was standing, there was no such problem. My suspicion is that in win10 you can only use the analog output to the receiver, but I can’t do this, because. the receiver is new and there are no analog inputs, only coaxial and optical. If anyone has this problem please help...