Mobius unmounts/disconnects when connected via USB.

Make these changes to your computer’s settings:

Windows 7/8:

Control Panel > > Power Options > Change Plan Settings > Change Advanced Power Settings > Hard Disk > Turn off hard disk after = Never

Control Panel > Power Options > Change Plan Settings > Change Advanced Power Settings > USB Settings > USB Selective Suspend = Disabled

Windows 10:

Control Panel > System & Security  > Power Options > Change When The Computer Sleeps > Change Advanced Power Settings > Hard Disk > Turn off hard disk after = Never

Control Panel > System & Security > Power Options > Change When The Computer Sleeps > Change Advanced Power Settings > USB Settings > USB Selective Suspend = Disabled

Mac:

Energy Saver > Uncheck "Put hard disks to sleep when possible"

If you still have trouble, try another USB cable.