Site clones from my client's nation to my developer sandbox are failing. We do happen to have voter registration pages. We removed those, but the failures are still happening.
In this case, the developer was working on a theme in his developer sandbox nation and wanted to see how it would look on the client's existing site. Another way to accomplish this without site cloning is to share the theme with the client's nation and use Preview mode to see how the theme looks on that site.
If you are also experiencing site cloning failures and this description doesn't help you, please comment below and email details to firstname.lastname@example.org.