Windows does not share mounted drives between login sessions of the same user (sshd and GUI/RDP).
Look for EnableLinkedConnections which should be set to 1.
reg query HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
When not, add the key to the registry.
reg add HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System /v EnableLinkedConnections /t reg_dword /d 1
It all seems to have NO effect since the credentials are not stored for the fileserver.