A mapped drive (e.g //devtools/public mapped to a drive letter) is not visible from the “Open” dialogs with elevated programs (e.g. Workflow Configuration). This issue was replicated under Windows 8, 10, 2012 and 2016.
This issue has been confirmed as "by design" by Microsoft Support. See http://connect.microsoft.com/VisualStudio/feedback/details/767400/folderbrowserdialog-does-not-show-network-drives-on-windows-8 for more details.
Ex: Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\system]"EnableLinkedConnections"=dword:00000001
Note: this may open security vulnerabilities to your system since this behavior was introduced for security reasons.