Reads SD but not portable HD

This is a good app but cant seem to read the portable Seagate Slim 1 TB hard drive I plugged into the USB port on the Ravpower device. The device powers the Seagate HD no problem so not sure why it wont read the HD. The instructions do mention that it will read USB flash drives. Havent tested that yet.

Dan from Canada about FileHub Plus, v2.0.022