I tried to connect 3 drives in the same manner as you. This time, the USB 2.0 port in the front is reporting a drive and it seems to working. I plugged my large drive into the rear bottom port. I then connected a new drive to the rear top port. The confirmation box was presented to format the drive. However, after the format appeared to complete. No additional "source" choice has become available. So not sure what this means. For my clarification, you have all 3 connected at the same time and all 3 plus the hopper drive appears on "sources" list?