VM Fusion Pro 7 and USB3

I've searched hi and wide, but can't get this question answered.

Fusion Pro 7 is said to add support for USB 3. I tried this with a USB 3 thumb drive under Mac OS 10.10, Yosemite, and it seems to work.

Tried it under 10.9, Mavericks, (same Pro 7), but the USB 3 thumb drive doesn't work.

Is Yosemite required for Pro 7 and USB 3 to work?

Thanks