Device Control - Exempt single device only

Running Enterprise Conole v. 4.5.1.0

I have a Device Control Policy setup to block access to Floppy Drives.  The software detects the devices on all workstations that the policy applies to.  I see the devices being blocked uder the "Add Exemption" list.

I would like to use the option to "exempt device only" but it is greyed out.  The only option I have is "all devices of this model"

Any suggestions would help!

Thank You!