It happens around 5th of February, 2020 until now and I just found out that it also mentioned on another website, zdnet.
The solution is:
- Start Windows PowerShell, Run as Administrator
- Reinstall and re-register Cortana fixed it. Run the following in an elevated (thanks to commentor dfrazier603)
Get-AppxPackage -AllUsers Microsoft.Windows.Cortana | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppXManifest.xml"}
And it’s back to work!