by Ken Task.
If you have any links, say, for example, to a Google Drive doc whose permissions are set to share with only those within a certain Google Domain. the backup routine of Moodle wouldn't know where a person plans to restore the course. If on same server in same Google Domain then things would work, but they would get busted IF those weren't the environment.
Are any of those items 'aliased' - meaning Moodle doesn't acquire a copy of it, but links to it to view/use.
'spirit of sharing', Ken