Retention policy is not deleting — four common causes

The policy has been active for weeks, the retention period expired long ago, and the documents are still there. Four causes explain almost every case.

Simulation mode is still running

Connect-IPPSSession
Get-RetentionCompliancePolicy | Select-Object Name, Enabled, Mode |
    Sort-Object Name | Format-Table -AutoSize

If Mode reads TestWithNotification, that is your answer.