DPM 2012 R2 Protection screen shows Backup to tape failed after successful backup

I'm using the latest DPM 2012 R2 fully updated and keep seeing this problem where the Monitoring screen will show the tape backup job for VM as completed with a number in the data written column but the Protection Status column on the Protection screen will list it as 'Backup to tape failed'. how do I know which one I can trust? Why are they showing inconsistent results?

It looks like the same problem as here:

DPM 2010 - Protection Status = Backup to tape failed
http://social.technet.microsoft.com/Forums/en-US/f5945658-67ca-4f26-8a15-9e3098db72ca/dpm-2010-protection-status-backup-to-tape-failed?forum=dpmtapebackuprecovery