Hello everybody, I can only agree with the previous speaker. I have the same problem. Use the current version of Windows 10 Pro (Build 18363.778).
Used Microsft drivers (which are very quiet)
Current manufacturer driver used.
Also older manufacturer driver used.
Problem:
I can access all 6 speakers through the sound test and it works. When I play a stereo recording there is only the output to the front speakers, the others are mute. This applies to different programs. Current games work with 5.1 or 7.1 and work.