Last night I had 2 of my defensive discipline clickies fail me outright: they went on cooldown after being clicked but I didn't get the buff.
This happened with both Defensive Will via Rayin's Gauntlets of Abhorrence and Defensive Discipline via Ring of the Clawed Guardian.
Last night it occurred in Sleeper's Tomb on the platform where Sleeper is, though I've had it happen in ToV and WW as well. I do not have any other discipline clickies, only defensives so I cannot say if all disc clickies are affected or not. I usually use my click before I engage a boss, though I've had the disc "poof" in this way and when engaging in "surprise you got too close!" combat. I use a hotkey to click the Gauntlets and the toon wears the Ring. I'm not sure what other feedback I can provide on this that would be helpful but would gladly do some testing.