Mapping shared folder fails if USB drive is connected after VM is started

[Rafcio]

I have a consistent situation where a shared folder that exists on a removable USB drive is inaccessible if the drive is connected after the VM is started. The situation is as follows. If the USB drive (on which the shared folder exists) is connected before the VM is started everything is fine, even though the shared folder is not auto mounted. However, if the VM is started before the USB drive is connected I can map the shared folder as (double backslash here that keeps being removed and replaced by a new line)
vboxsrv\sharedusb (its normal name), which seems to be successful, but any access attempts come back with an error message: Y:\ is not accessible. The parameter is incorrect. The USB drive auto mounts under /media, so it is available where it's supposed to be, but the shared folder is inaccessible. The only difference between successful mapping or not is whether the USB drive is connected before or after the VM is booted.

[aeichner]

Please reopen if still relevant with a recent VirtualBox release.