I am having some problems with both the 7 port and 10 port USB 3.0 hubs on a 2014 27inch Retina 5K iMac. Drives seem to mount or not mount in a random fashion. I get better reliability if I boot without anything plugged into the USB computer ports, then plug in the hubs. I’ve verified that the drives are ok and the hubs work with 10.6.8 on another computer.
Are you aware of any incompatibility issues with Yosemite, and has Apple notified it’s partners, such as yourself, of any issues?