Im getting the same issue as this with version 9.18.1.2601 of the PS module, I ended up having to use a api call to grab the tags.
function Get-ONTAPVolTags {
param (
[Parameter(Mandatory,
ValueFromPipeline)]
[string]$clusterName,
[Parameter(Mandatory)]
[string]$volUUID,
[Parameter()]
[ValidateNotNull()]
[System.Management.Automation.PSCredential]
[System.Management.Automation.Credential()]
$creds = [System.Management.Automation.PSCredential]::Empty
)
process {
$apiquery = "https://$clusterName/api/storage/volumes/$($volUUID)?fields=uuid%2Cname%2C_tags&return_timeout=120"
# Send the API request to get volume information
$result = Invoke-RestMethod -Method GET -Uri $apiquery -Credential $creds
# Return
$result._tags -replace(':','=') |ConvertFrom-StringData
}#END PROCESS
}#END FUNCTION
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