Exchange Full VSS Backup not truncating logs

I was having difficulty backing up a mailbox database with DPM and WSB by using a Full VSS Backup.  After migrating all the mailboxes to a new database I am still plagued by the same issue

Exchange VSS Writer (instance ed9f9795-9a91-43df-ab72-28138e983a3a:12) has completed the backup of database 'MDB09' with errors. The backup did not complete successfully, and no log files were truncated for this database.

However, a "vssadmin list writers" shows that there are no VSS Errors

Writer name: 'Microsoft Exchange Writer'
   Writer Id: {76fe1ac4-15f7-4bcd-987e-8e1acb462fb7}
   Writer Instance Id: {8015d94b-1b1e-4372-bd1c-8d98bbf23cd6}
   State: [5] Waiting for completion
   Last error: No error

This new mailbox database is part of a DAG with many other DBs that are backing up just fine.  There is no mailbox copy as of right now.

I'm at a complete loss with this DB, how can I find out why the logs are not truncating?