Incremental backups not working after upgrade to 6.0.6 from 5.0.23 on RHEL5

[eightball]

Upgraded from 5.0.23 to 6.0.6 on RHEL5 64 bit.

After resolving a syslog-ng issue that lots of others seem to also run into, I noticed that my incremental backups are not working.

Zimbra thinks they are working as the admin console and admin emails claim my incremental backups complete (manual initiated or nightly), but the backup itself takes less than 30 seconds which means my mailboxes are not being backed up.

I ran a full backup before upgrade, then another full after upgrade without any problems.

Has anyone else seen this problem? This is what I get when I try to run an incremental backup:

ZCS backup report SUCCESS:
Label: incr-20100416.174934.845
Type: incremental
Status: completed
Started: Fri, 2010/04/16 12:49:34.845 CDT
Ended: Fri, 2010/04/16 12:49:50.165 CDT
Redo log sequence range: 1511 .. 1512
Number of accounts: 44

Thanks

-john