I've recently signed up with Dropbox Backup and added my external hard drive.
I enabled backup for this drive, and selected 'Backup Now' rather than waiting for it to schedule a backup at 9am tomorrow morning.
Since doing so the drive remains at 90-100% usage, but not a single file has been uploaded in over 4 hours. It shows 0 bytes transferred in the Dropbox app.
How do I get it to do it's job and actually start the backup?