See more details there
https://answers.atlassian.com/questions/239823/invoke-command-in-powershell-script-doesn-t-work-when-invoke-it-from-bamboo-task-only

Steps to reproduce

Create Script task with PowerShell interpreter

$session = New-PSSession
Invoke-Command -Session $session -ScriptBlock {
    Start-Process "calc.exe"
}

Start agent on windows host under Administrative account
Add requirement to created plan to be sure it's executed at started Windows agent
Start plan

Expected: calculator window
Actual: nothing happened