Flash Drive only mounts through USB Hub I have a PNY 32gb flash drive, when trying to connect the drive directly to my Mid 2012 MBP (specs attached) the drive never mounts, doesn't list in diskutil as an unmounted drive either, however when I plug the drive into a Micro Innovations USB Hub (old ~ 2002) the drive mounts (albeit slowly).

On my iMac (Mid 2010 I7) the drive works perfectly in the machine or through Apple USB Keyboard.

Any help?
I had a similar thing with an old pen drive that was faulty. 
First thing I would do is go to the Console and check whether the OS complains when you insert the pen drive. In my case I would get a lot of I/O errors related to the USB device.
Reformatting and partitioning the thing with Disk Utility solved my problem (but I never trusted the drive again, I have to say)