Why are my Defender drives not displayed in the file manager window?

 

If you map a network drive to a resource using the drive letter typically assigned to a Defender device, you will not see the Defender drives in the file manager window when you connect the device.

This problem only occurs if you map the drive while the Defender device is disconnected from the computer. You need to disconnect the mapped network drive. To work around the mapping issue, it is recommended that you re-map the network drive using a drive letter from the end of the alphabet, for example, Z or Y.

This is a known issue with Microsoft Windows and removable storage devices and is documented here.