Posted this mainly for my own use. A client had a commercial business management application that could not “see” legitimately mapped drives, in this case, to select a target for a data backup. This registry fix resolved the issue.
Ran into a little glitch with two unrelated third party applications that relates to mapped network drives. Right after the Windows 10 upgrade, mapped drives were still in place, and the contents of these directories were completely visible from Explorer on the host machine, but not from inside the application software, as if they didn’t exist.
The solution is a missing Windows registry key at:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System.
Look for a key named “EnableLinkedConnections” and a DWORD data value of 1.
If this key is not present, you may have to add it manually. Spelling is strict, so be very careful.
Then reboot. Repeat for each workstation.
You may also have to remap the drive on the “server” machine.
That worked for me.