I understand that you can connect and see it to transfer files.. This is normal behavior.. But you have to enable tethering on the phone itself and tell it to share it via USB otherwise it won't work. Such as below you can see if I was plugged in via USB I could check that and my phone wouldn't see my phone as something like a drive for files.. It would set it up as a modem connection.
If you're doing that and it won't work.. Is the tethering activating? Such as mine shows an icon at the top left when tethering is on so I know it is... If it isn't.. Do you have tethering on your Sprint plan?
Sent from my T-Mobile Note 3 using AC Forums.