Xamarin Forms Powershell failure

When I create a Blank App(Xamarin Forms Portable) in VisualStudio 2015 (Windows 10), I get the below error.
Xamarin.Forms.2.0.0.6482 : Failed to initialize the PowerShell host. If your PowerShell execution policy setting is set to AllSigned, open the Package Manager Console to initialize the host first.

I have
1) run the following command in Powershell and relaunched devenv.exe
Set-ExecutionPolicy AllSigned
2) devenv.exe run as administrator

But no luck.