SATA to USB Adapter
I would not be surprised if the adapter is somehow faulty. The use of a second USB cord to get power violates the USB specifications and anyone that can't be bothered to follow this very basic USB specification is quite likely to violate some other specification.
I'd suggest returning the adapter if you can and getting one that powers the drive properly. That would be with a single USB plug for power and data, or with USB for data and a connection to a wall outlet for power.