When I installed your latest update (4.0) I initially saw all of my built-in card readers and the card readers in my printer in addition to my thumb drive. A pop up window suggested moving the built-in card reader to hidden, which I accepted. I was disappointed that the readers in the printer were not similarly handled but I was able to hide them manually. I would also note that my system's hard drive had been included in the list for the previous version and I had hidden it. It remained hidden in the new version. It is an internal SATA drive so I would not expect it to be listed at all. I now have only one thumb drive visible with 5 drives in the hidden list.
When I inserted a memory card into the built-in card reader it appeared in the list and I was able to eject it. It returned to hidden status. I repeated this with the printer and it does not appear to work. The drive remained hidden. I clicked on it in the hidden list and asked it to be stopped. After confirming that I wanted to stop drive in a hidden device it did so, but the card remained in the list with a red X even after removing the card.
Frankly I don't care because I use the reader in the machine rather than the one in the printer but I thought you might like to know about this.