VM settings failed to add device physical disk drive

Hello,

Server 2012 R2 using Hyper-V manager; have previously been able to add external USB hard drive to the host, make the external drive offline, then use the VM settings to add the external drive to a VM machine.

Just recently (last two weeks) I cannot add the external drive through the settings, get this error message:
'VM-ABC-EXCH16' failed to add device 'Physical Disk Drive'. (Virtual machine ID 37C70A3A-737E-478D-984F-32FA86349308)

In the event viewer that message appears as 14140.

Tested upon different VMs and also a different host with different VMs, also different external hard drives (and external drive works fine on local computer).  Nothing will attach.  As noted, this has worked in the past.  What can I do to resolve?

Thanks

TECHDLS