Restore snapshot from USB drive via CLI

[ken_networks]

Trying to restore a R80.30 snapshot image (stored on USB) via CLI

I have completed the following to mount the USB drive:

mkdir /mnt/usb
modprobe usb-storage
dmesg
mount /dev/sdb1 /mnt/usb
cd /mnt/usb
ls

Snapshot image is named 80_30.tar.

Then ran the following to import the image and revert:

set snapshot import 80_30.tar path /mnt/usb/ name 80_30
set snapshot revert 80_30

After issuing the revert command, nothing seems to happen.  There is no on-screen messages or progress bars.

Tried viewing snapshots using show snapshots but that returns nothing.

Any help here would be appreciated.