I have both Photoshop CC 2014 x64, and Illustrator CC 2014 x64 installed on my Windows 8.1 Update 1 system.
At present, I have run Fusion 5 v 16.2.1 as administrator and enabled the plug-ins for both of the above apps.
When I open Illustrator, the Fusion 5 plug-in works immediately and I am able to choose from all the fonts in the libraries/sets that I have set up
However, when I open Photoshop, it seems that the plug-in is not recognised, because the Fusion plug-in window does not pop up. Also, when I load an image with a missing font, Fusion does not offer to activate that missing font
Could this be anything to do with the TypeKit system that is part of Photoshop?