Are you running PowerCLI 5.1 build 1012425? This was a bug in their Environment script which is what is being called by WFA. Also, make sure that you enable "Set-ExecutionPolicy –ExecutionPolicy RemoteSigned" in your PowerCli window
Steps to fix issue with build 1012425
Navigate to the following directory path on the WFA server -- "C:\Program Files (x86)\VMware\Infrastructure\vSphere PowerCLI\Scripts\"
Right Click the file named - Initialize-PowerCLIEnvironment.ps1 and select properties.
Remove the ReadOnly flag and hit ok
Edit the file named - Initialize-PowerCLIEnvironment.ps1
Remove line # 9 - "$version = Get-PowerCLIVersion". This command will never run fails WFA every time.