Unable to install new RDS Session Hosts 2012R2

Question

We currently have an 2012R2 RDS environment running 8 farms across 12 session hosts from one connection broker. Recently I went to provision 2 new Session Hosts (one to a new farm and one to an existing) however they both fail with the following error in
the Server Manager Wizard:
Access is denied
The term 'Get-LocalMachineFqdn' is not recognized as the name of a cmdlet, function, script file, or operable program. Check the spelling of the name, or if a path was included, verify that the path is correct and try again.
I've also tried installing from PowerShell without success.
Has anyone come across this before? I haven't been able to find anything in my searches on the web let alone find anything of use in the event viewer.
Cheers,
Ryan.

Answer 1

When attempting to view the certificates via PowerShell I receive the following error, despite having the correct permissions:
PS C:\WINDOWS\system32> Get-RDCertificate -ConnectionBroker pv-rdcb02.ksgroup.com.au
New-PSSession : Access is denied
At C:\WINDOWS\system32\WindowsPowerShell\v1.0\Modules\RemoteDesktop\Certificate.psm1:34 char:19
+     $M3PSession = New-PSSession -ConfigurationName Microsoft.Windows.ServerManag ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : OpenError: (System.Manageme....RemoteRunspace:RemoteRunspace) [New-PSSession], RemoteExc
   eption
    + FullyQualifiedErrorId : PSSessionOpenFailed
Invoke-Command : Cannot validate argument on parameter 'Session'. The argument is null or empty. Provide an argument
that is not null or empty, and then try the command again.
At C:\WINDOWS\system32\WindowsPowerShell\v1.0\Modules\RemoteDesktop\Certificate.psm1:36 char:40
+     $RDCerts = Invoke-Command -Session $M3PSession -ArgumentList @($optionalPara ...
+                                        ~~~~~~~~~~~
    + CategoryInfo          : InvalidData: (:) [Invoke-Command], ParameterBindingValidationException
    + FullyQualifiedErrorId : ParameterArgumentValidationError,Microsoft.PowerShell.Commands.InvokeCommandCommand
New-Object : Cannot convert argument "6", with value: "", for "Certificate" to type
"Microsoft.RemoteDesktopServices.Common.CertificateRole": "Cannot convert null to type
"Microsoft.RemoteDesktopServices.Common.CertificateRole" due to enumeration values that are not valid. Specify one of
the following enumeration values and try again. The possible enumeration values are "None, RDGateway, RDWebAccess,
RDRedirector, RDPublishing"."
At C:\WINDOWS\system32\WindowsPowerShell\v1.0\Modules\RemoteDesktop\Certificate.psm1:96 char:9
+         New-Object Microsoft.RemoteDesktopServices.Management.Certificate `
+         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (:) [New-Object], MethodException
    + FullyQualifiedErrorId : ConstructorInvokedThrowException,Microsoft.PowerShell.Commands.NewObjectCommand
Does anyone have any thoughts?
Cheers,
Ryan.