Following up on our previous topic http://www.gravityhelp.com/forums/topic/conflict-with-backup-buddy-offsite-backup-transer Dustin from the ithemes BackupBuddy team has narrowed the problem down to
some sort of issue with "no conflict" mode in Gravity Forms causing this issue. Disabling "no conflict" mode on the Gravity Forms Settings page appears to resolve the issue.
It would appear that no conflict mode is going further than it was intended to and is also preventing some scripts from loading on other plugin settings pages which isn't ideal.
Here's the link to this issues BackupBuddy topic for anybody with an ithemes forum account http://ithemes.com/forum/topic/26774-get-a-404-error-when-trying-to-send-my-backup-offsite/