There is an issue with Windows 10 (I don’t know, if earlier versions do the same) that USB devices will be recognized, but will not get a drive letter assigned.
Usually what you can do, is every time open the drive manager and assign a new drive letter to the device.
But doing this often is a pain and cumbersome.
Third party fixes promise solutions (many times by altering something in the registry).
Fortunately, there’s an easy Windows-onboard solution that does not require any third-party software or registry modification.
- Open Command Prompt as Administrator (search for Command Prompt in the Start Menu, right click, Run as Administrator)
- Type ‘diskpart‘ and press Enter.
- Once in the DISKPART command prompt (it takes several seconds to load) type ‘automount enable‘ and press Enter.
That will re-enable automatically mounting new volumes, fixing the issue.