Yeah, but thinking about it a bit more, there may be another problem.
A lot of these pre-built enclosures have either a protected partition or virtual cd in the firmware with the vendor's software on it. That can cause all sorts of havoc with both OSX and Fusion (I had some hitachi drives that OSX simply wouldn't mount). If you can, disable any of that stuff on the drive.
I tend to avoid anything with built-in capabilities (like backup) because of that - and frankly, none if it works well anyway. I also repartition the drives before using them to remove any other funky crapware that they've included.
FWIW - I have had pretty good luck with the Western Digital USB 3.0 MyBooks, but what always works is to use a third-party enclosure and build your own drive.