After multiple issues with Snapshot and my webhost (https://premium.wpmudev.org/forums/topic/snapshot-managed-backup-didnt-run-as-configured#post-1307095) I am stuck with the last question of why the archives haven't been uploaded to the cloud yet and are only kept on my server.
It still might be some server side issues. I have only run 3 managed backups and that hardly is a big database to use for an argument. And all three of them were created during night time when the server issues have been showing up the most.
However, I've just been running multiple Managed Backups manually during daytime and all ended up locally on my server. But finishing with "Your backup has been successfully created and uploaded to WPMU DEV servers!"
I then went ahead and uninstalled WPMUDEV Dashboard and Snaphost. On reinstalling Dashboard nothing unusual happend. But when I reinstalled Snapshot I got "Server error status: error " - which might explain the problem for uploading. But it also means that there's someting off in the way that Snapshot checks if the upload to the cloud was successful.
I have another (bigger) multisite install on the same host where scheduled managed Snaphots have been finishing every night without any incidents while this site here has been giving me issues. Of course that doesn't rule out that it's a server side issue but it does feel like the issue is more likely to be found inside the wordpress install.
I've enabled support access. Hope that gives you enough information to look into things.