As far as I'm aware, OneAgent should report on network drives and report on them as mount points. The AppMon Host agent which is running on the host, does show all drives (10 in total, 7 local and 3 network file shares), yet the OneAgent doesn't report on the 3 network drives at all, I only see the 7 local mount points.
This is happening on a Linux host, but I see the same thing on a Windows host. On the Windows host, the 'dtuser' is part of the Performance Monitoring Users group on Windows. I have to admit that on the Windows host, there is a mapped drive that shows in Explorer but not as a drive under Disk Management, so I understand that it won't show in this case.
Is there a setting I'm missing perhaps?
From my experience, you will only see the local drives and not network drives. You can put in a RFE stating you use case and the Dynatrace Developers will review it an hopefully build that capability into the platform.