I have the same problem. Not difference between direct connection USB cable of my UPS (SVEN Pro 1000+) to USB3 port Mac Pro Late 2013 or USB2 port Thunderbolt Display or USB3 port ORICO 7ports USB hub connected to USB3 port Mac Pro. I never seen UPS icon at Save energy settings when upgrade from Mavericks to Yosemite.
Inside About this Mac detailed report USB section I can see my UPS as STD UPS MON V1.0.
NUT drivers and Upsilon monitor for Mac OS (under Darwin) in Terminal window also can't detect UPS.
At the same time in Windows 8 under Parallels 10 for Yosemite (works as virtual machine at external USB 3 disk drive) I can run Upsilon utility for UPS and can see all UPS parameters after "I say" Parallels to connect UPS to Windows 8 virtual machine instead of Mac.
My wife's MacBook Pro (late 2014 16 gig core i7 512 Gb flash) has the same symptoms.
I'd like to hear any ideas and recommendation.
Best regards.