Snapshot Import Error when trying to Move Multisite

I’ve downloaded and moved a backup file to, however when I do a “Scan / Import Snapshots” on the dev. site I get the following response.

Processing archive: (288.46M)

Error: Manifest data not found in archive.

The file size of 288MB is also very different from the size Snapshot is reporting on the original site which is 506MB.

Any thoughts of how to get a usable backup to move the entire site?