I saw that many people had a problem similar to that and tried all the solutions without any success.
I tried uninstalling oculus rift and its driver and reinstalling everything.
I tried disabling all my other audio outputs except Rift Audio
I made sure all the firmware of my devices was up to date
Here's what happens now.
For now, Oculus App is closed.
When I open the windows sound settings on the Playback tab I now see only Rift audio.
I right click on it, go in Advanced and click on the test button.
The sound is going through since I see the green bar and I hear the sound from the rift's headphones.
I now open Oculus App
Then try the test again
It still works, I still see the green bar.
But if I wait long enough, the sound will stop in a game or when I am in oculus home. (It usually is about 15 seconds)
If I press on the test button again, there's nothing. No green. No sound.
If I close Oculus App and do the test again. It works!
So I don't know what is causing that problem. Even the test doesn't work. And it only happens when Oculus App is opened. By default the "Exclusive Mode" is on but I tried unchecking that box since I though maybe an app was taking control of the audio. But it doesn't change anything. I know it's not conflicting with other outputs since I disabled them all except for the Rift... I also made sure the output was set to Rift Audio in Oculus App and also tried mirroring the audio. But nothing is working.
Looks like a bug in the Oculus software
It was working fine before. I'm not sure which update caused that problem... Anyone know any workaround to that problem? Thanks a lot!