Flipbox does not see network drives which were connected in Windows interface. For example, from "Open file" menu in Word there is no any network drives in explorer. Word was added in Flipbox as application.
1) Open Windows Registry and go to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System.
Create a DWORD key EnableLinkedConnections and set parameter to 1. Restart the machine ane check the operability. If it will not work try second variant.
2) Start command line inside Flipbox. For example: Open Flipbox and open CMD as side application. Add network drive manually in command line. To avoid disappearing after reboot use command "net use /Persistent:Yes" without quotes.