Oh, you Win 10 machine is part of a local domain? Seems to be the same issue as the below thread which unfortunately I can not see a solution in that thread
I’m running OSMC on a Pi3. Two USB disks are connected to it, with different media content.
I’m using a computer with Windows 10 to access these USB disks, which are shared on the network “automatically” by OSMC. That is, I haven’t configured anything related to sharing, smb or similar.
When I’m logging in locally on the Windows 10 computer, I can access the USB disks on the OSMC server using the osmc/ credentials. Even if I just connect a new USB disk to it, this too is automacally shared and…