Snapshot Not Backing Up All Multisite Databases

Have started using this plugin with a (test) multisite (3 sites) and trying to migrate to a new URL.
The issue I'm having is that the plugin isn't backing up all the database files.
It is backing up database files as "wp_ " but not "wp_2_" or "wp_3_"
Any ideas or the 'trick' to get it to work.