Sitecore PowerShell action to update the workflow and workflow state for all items in the ListView of the report.

Update workflow for all items.ps1

$processedItems = New-Object System.Collections.ArrayList

function SetWorkFlowAndState {
    [CmdletBinding()]
    Param(
        [Parameter(Mandatory=$true)]
        [Sitecore.Data.Items.Item]$Item,
        [Parameter(Mandatory=$true)]
        [Sitecore.Data.ID]$WorkflowID,
        [Parameter(Mandatory=$true)]
        [Sitecore.Data.ID]$WorkflowStateID
    )

    $Item.__Workflow = $WorkflowID
    $Item."__Workflow state" = $WorkflowStateID
    $processedItems.Add($item) > $null # ignore output of Add
}

foreach ($item in $allData) {
    SetWorkFlowAndState $item $actionData.WorkflowID $actionData.WorkflowStateID
}

if($scriptsession.Output.HasErrors) {
    Show-Result -Text
}

$processedItems | Update-ListView

Show-Alert -Title "Processed $($processedItems.Count) items."