I connected my JTAGIce MkII to one of the USB3 ports on my computer and it looks like it enumerated with "&"s in the identifier.
AVR Studio then blows up with the attached parsing error. You can also see the name in the Select Debug Tool Window.
you can see if I reconnect the MkII to a USB2 port, it enumerates without ampersands in the identifier. If I select that it works okay, but as soon as I select the other, it fails and I can't debug.
It's not a problem for me - I've just moved to another USB port, but I wanted to report the bug.