I updated my server machine (headless Mac Mini) to the latest Public Beta of Yosemite 10.4.4 a couple of days ago. Noticed that my z-wave triggers weren't happening and went looking for the cause. Apparently there's something in the latest update that hosed the FTDI driver. Downloaded a new copy of the driver and installed it. After a couple of restarts of Indigo Server and the z-wave interface all is well.
As Mat and Jay will tell you, don't run beta OS on your production machine....