Turn off mirroring of Windows-connected drives on Mac?

Using Parallels 11.1.1 (32312), El Capitan 10.11.1.

On the Parallels Preferences Devices tab, I have a USB drive assigned to my Windows VM.
Under "When a new external device is detected" I have selected "Ask me what to do" and also turned off "Mirror Windows-connected drives on Mac".

But the USB drive still shows up on my Mac desktop with a gold icon, and in Finder's Devices section in the sidebar.

I've tried to get Parallels to forget about the drive. I've ejected the drive from Windows, removed the drive from the USB hub, removed the permanent assignment from the Devices tab, reconected the drive.

Parallels never sees the device as new, never asks me what to do. It probably did some time ago, but no longer does.

I can change the assignment to Mac, and the device will disappear from the VM.

When I change the assignment back to the VM and restart the VM, it reappears in the VM but remains visible on the Mac.

If I eject the drive from the Finder, it will disappear from the VM.

With the drive ejected but still connected to the USB hub, I can select Devices -> External Devices from the Parallels menubar, and pick the external drive, and it is automatically connected to the VM. Now it shows up in Finder's Favorites section, and appears on the Mac desktop as a blue, not gold, icon.

In the "reverse" direction, I have SmartMount turned off in the VM configuration, and external drives assigned to the Mac do NOT show up in the VM, which is what I intended. For instance, I am not interested in Windows seeing my Time Machine drive. This Mac-connected non-smart-mounted drive appears in the Finder Devices section, and on the Mac desktop with a gold icon.

In the VM configuration, Sharing Options, I have "Access windows folders from the Mac" enabled. If I turn off "Shortcuts to virtual disks on the Mac desktop," the desktop icons will disappear, but the C and USB drives still appear in the Finder Favorites.

The NTFS-formatted USB drive has .DS_Store files on it (visible from Windows). Since OS X cannot write to NTFS, I presume this occurred because the drive was connected to Windows but browsed in the Finder, and that Finder was able to write to the drive indirectly through Windows.

While turning off SmartMount can prevent Windows from seeing drives assigned to the Mac, there doesn't appear to be a way to prevent the Mac from seeing drives connected to Windows when sharing of Windows is in effect, though the Windows-connected drives may show up with a blue or bold icon, and as Devices or Favorites, for reasons I do not understand.

If I stop sharing Windows with the Mac by turning off "Access Windows folders from the Mac" (or I presume if I isolate Windows from the Mac), the drive will disappear from the Mac desktop and Finder - along with my C drive. But I do not want to stop all sharing, just the sharing and visibility of the external drive.

The Help page states the mirror option would "Choose to mount Windows-connected external NTFS drives to Mac."

The Parallels Desktop User's Guide (for Parallels 11) briefly explains:

Mount Windows-connected external NTFS drives to Mac
If you connect an external NTFS drive to Windows, you can make it available in OS X as well. To do so, choose Mirror Windows-connected drives on Mac.

In some cases I do see that the drive is not connected to the Mac as a "device", but only if ejected from Windows and then remounted through the Parallels menu. In any event, the drive is still visible in Finder's Favorites. It can be manually removed from Favorites, but will reappear there after a VM restart.

Wherever the drive is - in Devices or Favorites, and with a gold or blue icon the Desktop - the drive seems to always be available in OS X.

What does the preference to "Mirror Windows-connected drives on Mac" actually do, and is it possible to block the Mac from seeing external devices connected to Windows?

Thank you in advance for your help.