RN102 - Unable to create a volume of a USB disk

Hi,

I connected a Seagate external hard drive (https://www.amazon.com/dp/B093BVQYYM)  to my RN102. By logging into the RN102 using ssh, I can see that the device is recognized and I can even create partitions, format as ext4, and mount. My intention is to use this disk as backup target. However, I am not able to select the mount point as target for backups. 

I then removed partition from the disk, thinking that I will create a "volume" from the UI. But in "System => Volumes" page, the UI doesn't show the new disk so I cannot create a volume. 

Any idea on why UI doesn't show the disk, especially when it is recognized by the OS?

Thanks,

Raghu