We have a Multisite installation at http://www.my-fin.co.za, where I just can't get Snapshot Pro to actually create a managed backup.
I've set it to run every evening at 11 PM, but to no avail. Often I'd login in the mornings only to see "Automatic backup currently running" - but no backup ever appears in the cloud or on Dropbox.
Unfortunately I can't deactivate/activate plugins to find a culprit (if in fact it is a conflict), since it's a live site containing several other live sites.
I have in the meantime installed another backup plugin, WPB2D, since saving backups is critical - and that seems to be working fine, backing the whole MS installation up to Dropbox.
I have allowed support access in the WPMU DEV Dashboard, in case it's needed.
Hope to hear from you soon!