What windows 10 are you using? Is it the latest update?
Sorry about it, I'm annoyed and tired so yes... info is missing.
So here is what I think is relevant; probably I missed out thing so I'll try to add them if needed.
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Windows 10 Pro 64bit latest update (Feb. 07.) Build: 19042.985
I use multiple audio output and I switch between them (the issue always happens when I switch; but even when I don't it happens as well)
All drivers are up-to-date (windows audio drivers, realtek audio, etc.)
I have tried every "fix" I could find that is at least remotely similar to mine. (re-install driver, restart in safe mode and so on)
Troubleshooter did not give any errors.
It happens with any audio device I try; no matter the type of connection it has (HDMI, USB, 3.5mm audio, DVI)
MS support doesn't even work for me for... some reason so that is a luft.
1 thing I thought could be the problem was the "Focus assist" but it is turned off completely, at least that is what it wants you to think.
P.S.: Sometimes that it's muted only shows up when there would be something to make a sound (line when you change the volume on the taskbar), before that it shows as having sound. I don't know if it makes sense.