Scheduled backups are not triggering. Any ideas why?

I installed Snapshot on a development WordPress network. When I create a snapshot and choose the "Save settings and Backup now" option everything works fine. However, when I schedule backups of a site they never happen.

Initially I setup once per day backups of a couple sites. After a few days and no backups, I created a new snapshot of a site scheduled for every 5 minutes and still no backups are being created.

Any ideas why this plugin is not working?

I have made sure to visit the individual sites to make sure that wp-cron will be triggered. Also, I am running on a Windows Server with IIS so I do not have Unix cron as an option.