I am not sure exactly what causes it but I have been using classy restoration (and also well of radiance) a lot and quite often I trigger restoration X2 and take a big hit of damage and it will entirely clear the restoration buff. I notice it the most with the missle barrage from cabal (the blinding/slow missles). Almost everytime in the duality dungeon if I trigger restoration knowing I'm about to be hit by the missle barrage it immediately clears and I'm at critical health and not healing. Healing grenades will give you cure and then missile barrage and no restoration! I've also seen this happen in Well of Radiance where the healing just....stops. Which is really pretty bad. Expect to get healing in a well and all of a sudden you are just dead. Again, not sure if it's the big burst of damage that clears restoration or if it's something specific like the missle barrage. Please look into this and see if you can resolve, kind of a pain. Thank you!