One of my customers running the latest OSX release (10.10 - Yosemite) emailed me regarding my devices not connecting to his Mac. After much investigation the problem was due to Apple re-writing their USB drivers, in particular closer attention to detail within packet sizes on a transmission. Previously, Windows and Linux truncated excess data in a packet and parsed only the information it requested. Yosemite takes this a step further and should a packet size be inconsistent, It will abort enumeration completely.
Yosemite also keeps a close watch on Fat12 file systems and doesn't seem to like non standard parameters. It is a good sport in this regard and will allow the data to be passed without a big fuss.
Having found these faults, a fix in on the way. It is complete and is in testing. Currently only tested in a VM, though I'll be visiting a friend with the latest Macbook for real world testing in the coming days.
If you have my Gen2 products and are using a Mac, email me for the latest Joey Squinson firmware update!