So it kind of worked.
I did the first step uninstalling Intel SST (deleting from device) with the difference that it didn't got back thru Windows Update but by running sound troubleshooting.
But the situation got worse, because even though the SST was gone and back again, the sound icon in the task bar had now a red X over it, which it didn't have before, even though not operating.
So I ran the System File Checker and after that I restarted the computer and the situation was the same, red X over sound icon. So I uninstalled SST and ran Checker again and restarted. And this time sound worked! But this time also, it demanded a new restart to complete sound configuration (SST).So I restated, and now red X again, not working.
Then I uninstalled SST again and noticed that the red X was gone somewhere while sound troubleshooting was running, and then red X came back and STT was reinstalled. So I uninstalled SST and when running troubleshooting and seeing the red X was gone, I stopped troubleshooting. And it remained 'X free'
Current situation is: sound working, SST appearing in "System Devices" list and system notifications warning to restart computer to complete SST configuration (which I'll obviously not do). For now if I ever need to restart I´ll have to repeat this operation, and hopefully it will work again.
Therefore it's not a "problem solved" situation, but rather a "problem managed" one. So it should still be reported to Microsoft developer's team.
Anyway, thanks for your prompt answer that allowed overcoming this issue.