Initially after upgrading to 1607 on 3rd August, Coratana's voice input was working well. Even searching in lock screen wasn't an issue. However, yesterday, after chatting 30 minutes in Skype Preview video call on low battery, microphone stopped working. I checked if my Realtek Audio Manger was running, and it was not, as well as Coratana could not hear me. So I rebooted, Realtek Audio Manager poped-up, Cortana responded to "Hey, Cortana" and everything was fine...except "win+c" was not working. Nothing pops-out.
Gradually, after an hour of use, Cortana runs badly overall. She either
does not respond to "Hey, Cortana" or responds lately, the overall
speech recognition is not smooth and laggy, lock screen Cortana isn't working.
Rebooting fixes the issue temporary. After 1 hour it all starts again. "Win+C" doesn't work no matter how many times I reboot.
To point out, the microphone IS working. Skype test call, Voice Recorder and voice input in apps run smoothly. And Cortana does search in web, files, apps. Reminders and other commands ARE WORKING. So microphone is not likely an issue.
What I tried so far:
sfc /scannow - Says: "Windows Resource Protection did not find any integrity violations"
Ccleaner Registry Check - fixed 190 issues, well did not resolve the issue, obviously.