backup not working on multisite

Previous versions of WPB2D (1.4x) worked flawlessly on my multisite install. When I upgraded to v1.4.5 the backups stopped working correctly. It reaches 49% then says its uploading the backup in chunks (which is normal, except I used to see a 99% message). It times out (says there has been no backup activity for awhile) and tries to start over, but never completes. When I empty the backups directory and manually run the backup, it goes through the same process, and a backup is sent to my dropbox account. But the plugin doesn’t recognize it is finished and never states the file count backed up message or that the backup is complete.
When I leave it alone to run scheduled backups, they don’t complete and I need to click the “Stop Backup” button, empty the backups folder and run it manually.
Do you have any suggestions for troubleshooting that I can try? I use v1.4.5 on a second WordPress site (not multisite) and it works flawlessly just like the previous versions.

http://wordpress.org/extend/plugins/wordpress-backup-to-dropbox/