I SSH'd to the ESXi server and ran the following command which showed that the USB device was connected but also showed that the usbarbitrator service wasn't running.
esxcli hardware usb passthrough device list
I forgot that I was forced to disable this service when I first setup the server in order for ESXi to recognize an attached USB Hard Drive as a Datastore. I re-enabled the service to run temporarily by using the command below.
/etc/init.d/usbarbitrator start