Executing NCM script with PowerShell

I'm just starting to get my head around the powershell/sdk goodness and have a few queries based on the example here: https://github.com/solarwinds/OrionSDK/blob/master/Samples/PowerShell/NCM.ExecuteScript.ps1.

Credentials

If I configure the logon as username password :

$hostname = "MyOrionServerName"
$username = "MyUSerName"
$plainpass = "MyPlainTextPassword"
$swis = Connect-Swis -v2 -host $hostname -username $username -password $plainpass

The script completes and produces the results as expected.

However, I'd rather not have plain text username/password combination in my script, so changing to certificate based credentials, and running the script in ISE as administrator:

$hostname = "MyOrionServerName"
$username = "MyUSerName"
$swis = Connect-Swis -Certificate

I get the error:

Invoke-SwisVerb : System.Data.SqlClient.SqlException --> String or binary data would be truncated.
The statement has been terminated.
At C:\scripts\NCM.ps1:45 char:1
+ Invoke-SwisVerb $swis Cirrus.ConfigArchive Execute @($nodeIdList, $script, $user ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (:) [Invoke-SwisVerb], FaultException`1
    + FullyQualifiedErrorId : SwisError,SwisPowerShell.InvokeSwisVerb

at this:

 Invoke-SwisVerb $swis Cirrus.ConfigArchive Execute @($nodeIdList, $script, $username) | Out-Null

and the job fails to complete.

Any input here appreciated.

Output

I have added the (working) code to a template we have for sending emails.  When the job completes, Write-Host$outputpresents to the debug window nicely formatted text.

If however I send $output to the email, the text just becomes a single continuous string:

I've tried ConvertTo-HTML:

$($output | ConvertTo-Html -fragment | out-string)

which produces the completely non-helpful:

Now, in all honesty, I'm nowhere near a PowerShell expert, so I'd be gratful for any pointers on what I am (clearly) doing wrong that is stopping the text being a nicely formatted table

Thanks

Stuart