Been working on Amber shaper heroic using the strat of having a tank continuously shaped in p2. The tank is stacking debuffs on both the boss and the monstrosity, raid member shaped during p2 are responsible for interrupts and any stack help they can give while maintaining the energy to stay alive till we break them out. However we have encountered an issue where we our shaped players complain that they cannot get the interrupt to go off despite hitting their keybind, and attempting to press the button on the action bar. At first I dismissed this as a poor excuse for not having the focus to complete the role, however when I was shaped later in the raid night I also encountered the issue. Despite being in melee range of the boss, I was unable to use the 1(interrupt) ability. Perhaps I'm forgetting a mechanic that stuns, or in some way inhibits the ability of the shaped players to use it? Or is their some form of application CD from our tank stacking the debuff? Hopefully I'm simply stupid and am missing a mechanic rather then this being a bug.
(Dps are not stacking the debuff on the monstrosity at all, simply using the 1 key to interrupt the monstrosities cast)