We have recently published two articles to help cleanup recoverable items when a mailbox is placed on In-Place Hold or Litigation Hold or has single item recovery enabled, you’ll want to preserve the mailbox data until the hold is removed or single item recovery is disabled. In this case, you need to perform more detailed steps to clean up the Recoverable Items folder.
The detailed steps are located here:
Office 365: Delete items in the Recoverable Items folder of cloud-based mailboxes on hold – Admin Help
On-Premises: Clean up or delete items from the Recoverable Items folder
I have created a script will gather the MRM configuration for a given user. It will collect the current MRM Policy and Tags for the Exchange Administrators to be able to troubleshoot MRM issues. If you have MRM woes and need to collect data this script will do it for you.