Something is off with Paladin Threat generation.
Threat is not a value reported anywhere in the GUI. We all have addons to measure Threat, but they don't read the mobs Threat table. Instead they do their own calculation which we hope mimics the Blizzard one closely.
I make that statement to say I don't have any empirical evidence of a bug with Righteous Fury and the amount of Threat it's adding.
I have circumstantial evidence of losing threat even when the Addons do not show the party member with enough threat to gain the mobs aggro. I have further circumstantial evidence of losing threat in situations where I did not lose threat prior to 2.3.
I have the coincidental evidence of Righteous Fury being bugged in other ways (Mana Cost, Counted twice for Dispell).
I have corroboratory evidence of other Paladins both on the MainTankadin boards and the Official WoW Boards reporting that they are producing less threat this patch than before.
I have conjecture that the changes made to Righteous Fury this patch, to work with the altered Fanaticism talent, have caused a Bug in the amount of Threat Righteous Fury and the Talented Righteous Fury are generating.
Threat is the first task of the tank. If the mobs not hitting you all your hit points and armor don't mean much.
I haven't mentioned this to anyone in Mal Katai. I hate to be the kind of guy who blames every problem he's having in an instance on a "bug". Especially one that for which I can not find any empirical evidence. But at the same time, I know I risk each group that asks me to tank, and I further risk people forming opinions on my ability to tank based on this "bug".
By trade, I'm a coder (Computer Programmer). I know how hard it is to debug a large program, especially when the user presents an intermittent bug, or a bug that is difficult to describe as this one would be.
I make the assumption that a Blizzard Programmer has the ability to turn on an interface that shows him the mobs Threat table and he can watch the values as a test Paladin fights a mob. If those values look accurate, he's likely think everything was okay. I would if that programmer/tester was me.
I'm not going to stop tanking. Hopefully, when the other bugs with Righteous Fury are fixed, this one will be as well.