>>> I have confirmed there are no snapshots of this VM.
How did you do that? The Snapshot Manager may not show existing snapshots if there was an issue with deleting one. To verify whether an VM has an active snapshot, check e.g. the virtual disk's file name in the VM's settings. If it ends with s.th. like "-00000x.vmdk", then the VM has one, or more active snapshots.
In such a case you may use "Snapshot" -> "Consolidate" or - if available - "Snapshot -> "Delete All". If that doesn't work, create another snapshot, and run "Delete All" after that.
André